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CALIFORNIA  STATE  MINING  BUREAU 

FERRY  BUILDING,  SAN  FRANCISCO 
FLETCHER  HAMILTON  State  Mineralogist 


San  Francisco] 


BULLETIN  No.  85 


[August,  1918 


>L 


Platinum  and  Allied  Metals 


IN 


California 


IJBRARY 

bixvVi_t\Sl  FY  OF  C.\LiFORNlA 
DAVIS 


CALIFOBNU,  STATE  PRINTING  OFFICE 

SACRAilENTO 

1919 


..A 


KfBKARV 

UNIVERSITY  OF  CALIFORWA^ 

DAVIS 


r 

i 


CALIFORNIA   STATE    MINING   BUREAU 

FERRY  BUILDING,  SAN  FRANCISCO 
FLETCHER  HAMILTON  State  Mineralogist 

San  Francisco]  BULLETIN  No.  85  [August,  1918 


Platinum  and  Allied  Metals 


IN 


Califo 


rnia 


BY 

C.  A.  LOGAN 


LIBRARY 

OF    THE 

UNITED  STATES 
DEPARTMENT  V)F  AGRfCULTURE 


Book 

8—1577 


CALIFORNIA  STATE  PRINTING  OFFICE 
SACRAMENTO 
1919 
46903 


CONTENTS. 


Page 

LETTER  OF  TRANSMITTAL, 7 

INTRODUCTION   9 

Purpose  and  Scope  of  the  Report 9 

Properties,  Uses  and  World  Supply  of  Platinum  Metals 11 

Geography 14 

Relief 15 

Table  of  Production  of  Platinum  Metals 17 

DREDGING 18 

Introduction 18 

Prospecting  Ground  for  Dredging 19 

Feather  River  District 20 

Upper    Feather    River 22 

Resume    22 

Tuba  River  District 23 

American  River  (Folsom-Natoma  District) 27 

Upper  American   River 29 

CosuMNES  River 30 

Mokelumne  River 31 

Calaveras  River 32 

Tuolumne  River  33 

Merced  River 33 

SUMMARY  OF  NEWER  DREDGING  FIELDS  IN  CALIFORNIA 34 

Trinity  River 34 

Klamath   River 36 

Scott  River 37 

Sacramento  River 37 

Clear  Creek 38 

Cottonwood  Creek  38 

Butte  Creek 38 

Bear  River 39 

Other   Streams 39 

SEA  BEACHES 41 

Del  Norte  County 41 

Humboldt  County 41 

Laws  Affecting  Land  Under  Tidewater 42 

Analyses  of  California  Black  Sands 43 

OTHER   OCCURRENCES    44 

Mendocino  County  44 

Tehama-Shasta   Counties   48 

Beegimi  Creek 48 

Yolo  County 50 


IV  CONTENTS. 


I 


Page 
HYDRAULIC    MINING    52 

Del  Norte  County 55 

Topography  and  Relief 55 

Drainage  and  Water  Resources 56 

Geology     57 

Distribution    of   Platinum 58 

Origin  of  the  Platinum 63 

Klamath  River  64 

Salmon  River  District 68 

Topography  and  Relief 68 

Drainage  and  Water  Resources 70 

Geology   72 

Rocks  Originally  Sedimentary 73 

Altered   Igneous  Rocks 74 

Old  River  Terrace  Deposits 76 

Origin  of  Placer  Gold 76 

Occurrence  of  Platinum 77 

Junction   City   District 82 

Geology 82 

Production   of    Platinum 84 

Lower  South  Fork  and  Main  Trinity  River 85 

Hayfork  of  Trinity  River 90 

PLATINUM  IN  PLACE 93 

Shasta  County   93 

San    Bernardino    County 94 

Del  Norte  County 94 

Trinity  County 94 

San  Luis  Obispo  County 95 

RECOVERY  OF  PLATINUM  FROM  CONCENTRATE 96 

Hydraulic  Mining 96 

Dredging    97 

Methods  Used  in  Feather  River  District 97 

Methods  Used  in  Yuba  River  District 99 

Methods  Used  in  Natoma  District 100 

La    Grange    Method 100 

IDENTIFICATION  AND  METALLURGY  OF  PLATINUM  METALS 102 

Detection     102 

The   Glow   Reaction 102 

Metallurgy   of    Platinum 104 

POSSIBILITIES  OF  INCREASING  PLATINUM  PRODUCTION—. 105  ■ 

ANALYSES  OF  PLATINUM  GROUP  METALS  FROM  CALIFORNIA 109 

PRODUCERS  OF  PLATINUM  METALS  IN  CALIFORNIA,   1917 110 

INDEX    112   ■ 


CONTENTS. 


ILLUSTRATIONS. 


Photographs —  Page 

1.  Dredge  No.   16,  Hammonton.     Equipped  with  2  stackers  to  comply  with 

regxilations  requiring  a  clear  channel IS 

2.  Detail  of  bucket  line,  Dredge  No.  14,  Hammonton.     Buckets  hold  17  cubic 

feet  and  weigh  2  tons  each 23 

3.  Bedrock  cut  and  sluice,  Orleans  Bar  Hydraulic  mine,  Humboldt  County_     53 

4.  The  Orleans  Basin,   Klamath  River,   Humboldt  County 66 

.5.     The    Salmon    Mountains,    looking    east    from    Crapo    Mountain    toward 

Mount  Shasta 69 

6.  Hancock  Lake,  elevation  6317  feet.     Type  of  snow-fed  basins  whicli  lie 

at  the  sources  of  streams  in   the  Salmon  Mountains 71 

7.  Bank  of  pay  gravel  and  overburden,  Bloomer  mine,  5  miles  below  Forks 

of  Salmon,  Siskiyou  County.     Tj'pical  Quaternary  terrace 'deposit 75 

5.  Two  giants  working  under  pressure   of   457   feet.     Red   Hill    (Michigan- 

Salmon)    mine,   South  Fork  of  Salmon  River -- 78 

9.     Hydraulic  Mining  near  Sawyers  Bar,   Siskiyou  County 81 

10.  Huelsdonk  Submerged  Table  Concentrator 101 

Plates — 

I.      (a)    Photomicrograph    of    platinum    metals    from    Clear    Creek,    Sliasta 

County    13 

(b)  Photomicrograph  of  platinum  metals  recovered  by  cleaning  bed- 
rock of  hydraulic  mine  at  Sawyers  Bar,  on  a  bencli  of  Salmon  River, 
Siskiyou  County 13 

11.  Outline   Map   of   California 14 

III.     Geological  Map  of  Del  Norte  County 55 

IV.     Geological  Map  of  the  central  part  of   Salmon   River  District,   Siskiyou 

County    72 


I 


I 


II 


« 


LETTER  OF  TRANSMITTAL. 

To  His  Excellency,  the  Honorable  William  D.  Stephens, 
Governor  of  California. 

Sir:  The  attached  report  represents  the  result  of  several  months' 
field  work  which  was  begun  at  the  request  of  George  Otis  Smith, 
Director  of  the  United  States  Geological  Survey,  and  was  carried  on 
during  the  summer  and  fall  of  1917  in  co-operation  with  geologists  of 
the  Survey.  It  is  anticipated  that  the  report  Avill  ultimately  be  pub- 
lished l)y  the  above  organization  as  part  of  a  report  on  our  domestic 
platinum  resources. 

Meanwhile,  the  inquiries  which  come  to  this  Bureau  daily  on  the 
various  phases  of  platinum  production,  indicate  that  there  is  immediate 
need  of  a  comprehensive  and  up-to-date  report  on  the  subject.  The 
domestic  production  of  the  platinum-group  metals  is  limited,  Cali- 
fornia's placer  gold  mines  and  dredgers  are  the  principal  contributors, 
and  the  largest  domestic  reserves  of  the  metaLs  are  also  found  in  this 
state.  The  present  report  is  intended  to  answer  the  numerous  questions 
of  those  who  are  alive  to  the  nation's  need  of  an  increased  supply  of 
these  metals,  but  who  have  been  unable  to  find  anj'  exact  or  exhaustive 
treatment  of  the  subject  in  recent  technical  literature. 

Respectfully  submitted. 

Fletcher  Hamilton, 

State  ^lineralogist. 

August  20,  1918. 


I 


.*! 


INTRODUCTION. 

Purposes  and  Scope  of  the  Report. 

The  field  work  for  this  report  was  undertaken  for  three  main  purpose.s. 

It  was  desired  to  gather  and  make  readily  available  all  the  information 

to  be  had  regarding  production  of  platinum  metals  in  California,  to 

bring  home  to  the  owners  of  properties  where  these  metals  occur  the 

absolute  necessity  of  saving  and  marketing,  for  urgent  domestic  uses, 

every  ounce  mined ;  and  to  reach  some  definite  conclusion  regarding 

!  the  future  of  platinum  production  in  this  state.     The  work  was  made 

j  necessary  by  the  serious  conditions  caused  by  an  unprecedented  demand 

I  for  platinum,  occurring  at  a  time  when  importation  has  been  inter- 

I  rupted.     Old  sources  of  supply  in  Russia  have  failed  us,  and  new  fields 

I  have  been  called  on  to  .satisfy  the  needs  of  the  acid  manufacturers,  the 

chemist  and  experimenter,  and  the  maker  of  electric  apparatus.     It 

was  necessary  to  take  stock  of  our  resources  in  this  metal,  which  has 

become  so  important  in  industries  vital  to  our  success  in  the  serious  work 

on  hand  in  Europe. 

The  work  was  done  at  the  request  of  the  United  States  Geological 

I  Survey,  in  co-operation  with  geologists  of  that  organization.     Every 

I  active  mining   district   in    California,   where   platinum   is   found,   was 

I  visited.     Because  of  the  fact  that  it  occurs  in  gold  placers,  and  its 

,  recovery  involves  only  a  little  extra  care  in  addition  to  that  required  for 

I  saving  the  yellow  metal,  there  is  not  much  justification  for  failure  to 

save  it.     There  are  few  placer  properties  in  the  districts  visited,  where 

the  sale  of  platinum  metals  recovered  would  not  more  than  pay  at 

present  prices  for  the  labor  involved  in  getting  them  out  of  the  black 

sand.     This  is  true  alike  of  dredgers  and  hydraulic  mines.     This  work 

can  be  postponed  in  most  eases  till  spare  time  is  available,  so  it  need 

not  interfere  with  routine  duties. 

Most  small  oi^erators  were  found  to  be  unacquainted  with  the  simplest 
methods  of  increased  efficiency  in  this  line  and  were  not  doing  as  good 
work  as  is  desirable.  Both  hydraulic  mining  and  dredging  are  big- 
scale  operations,  carried  on  to  handle  large  yardages  at  low  cost.  There 
are  losses  of  finely  divided  gold  and  platinum  in  both  cases  which  are 
unavoidable  and  are  expected.  In  hydraulic  mining  the  less  occurs  in 
the  sluices  because  of  the  inability  to  save.  With  the  dredgers,  it  occurs 
principally  where  the  bedrock  is  hard  or  uneven,  and  can  not  be  cleaned 
by  the  buckets. 

The  territory  covered  was  so  large  that  attention  had  to  be  limited 
quite  closely  to  the  main  purposes  of  the  trip,  which  were  immediately 
practical  in  character.     The  result  was  that  extensive  or  sy.stematic 


10  CALIFORNIA   STATE   MINING   BUREAU. 

geological  work  could  not  be  carried  on.  It  must  be  understood,  that 
such  notes  as  occur  herein  on  the  geology  of  the  districts  visited,  repre- 
sent the  impressions  gained  by  hurried  reconnoissance  work.  In  the 
northwestern  part  of  the  state  an  effort  was  made  to  study  certain 
districts  far  enough  to  give  basis  for  an  intelligent  opinion  regarding 
the  origin  of  the  platinum.  This  directed  attention  to  the  distribution 
of  serpentine  especially,  and  resulted  in  the  mapping  and  outlining  of 
serpentine  occurrences,  with  an  inquiry  into  the  possible  relation.ship 
of  serpentine  and  the  platinum  metals.  In  general,  it  may  be  said  that 
the  results  of  the  work  confirm  strongly  the  hypothesis  that  the  platinum 
had  its  origin  only  in  basic  igneous  rocks  of  the  peridotite  type.  There 
were  certain  conditions  observed  which  might  be  interpreted  as  con- 
tradictory to  this  hypothesis,  and  which  ought  to  be  examined  more 
closely  before  a  final  statement  is  allowable. 

No  complete  survey  of  the  state's  platinum  metal  resources  has  been 
made  in  the  past.  David  T.  Day  made  an  investigation  about  20  years 
ago  with  especial  reference  to  the  occurrence  of  osmium  in  northern 
California  placers.  Day's  work  was  reprinted  as  a  part  of  Bulletin 
193  of  the  United  States  Geological  Survey.  The  occurrence  of 
platinum-group  metals  is  mentioned  in  a  casual  way  by  Lindgren  in 
his  exhaustive  work  on  Tertiary  Gravels  of  the  Sierra  Nevada.  These 
metals  are  also  mentioned  in  various  reports  of  the  State  Mineralogist 
of  California,  but  nothing  very  definite  has  ever  been  known  of  thera 
in  California,  beyond  the  fact  that  they  occur  widely  distributed,  in 
very  small  quantity.  The  writer  of  the  present  report  has  attempted 
to  make  definite  statements  only  where  based  on  results  which  have 
been  obtained  on  a  working  scale. 

A  large  number  of  properties  reputed  to  be  platinum  producers  were 
found,  as  a  result  of  visit  and  investigation,  to  have  no  claim  to  the 
title.  Similarly,  reports  of  platinum  ores  in  place  in  minable  quantity 
have  proven  without  foundation,  although  there  are  several  apparently 
authentic  cases  where  the  metal  has  been  identified  in  very  small 
amount.  The  tendency  of  promoters  to  capitalize  the  credulity  of 
their  acquaintances  and  to  sink  money  in  search  of  these  precious  metals 
in  places  M'here  failure  is  forecasted  by  all  conditions,  is  especially 
deplorable  now.  In  addition  to  the  loss  involved,  the  public  is  made 
distrustful  and  loses  interest  in  legitimate  mining  enterprises,  being 
often  unable  to  distinguish  a  project  with  merit  from  a  wildcat  propo- 
sition. A  consideration  of  our  known  platinum  resources  as  described 
in  the  following  pages  does  not  indicate  the  presence  of  any  undeveloped 
mining  property  which  could  be  profitably  exploited  solely  for  its 
]ilatinum  metals  content.  There  are,  however,  certain  districts  where 
the  platinum  metals  and  gold  occur  together  in  amount  sufficient  to 


PLATINUM   AND   ALLIED    METALS.  11 

invite  close  investigation,  and  where  the  value  of  the  ground  for  gold 
mining  is  greatly  enhanced  by  the  presence  of  platinum  metals. 

Our  greatest  reserves  of  these  metals  are  no  doubt  locked  up  in  Sierra 
Nevada  gravels  of  Tertiary  age.  That  in  the  dredging  fields  of  Central 
California,  and  in  the  Quaternary  gravels  of  the  northwestern  counties, 
is  more  readily  available  and  is  the  present  source  of  supply.  Some 
of  the  first  class  of  deposits' are  now  being  reopened,  but  anti-debris 
requirements  are  so  stringent  that  no  extensive  hydraulic  work  in  the 
Sierras  is  probable.  The  possibilities  of  our  dredging  fields  and  of  the 
terrace  deposits  of  the  northwest  are  covered  very  fully  in  this  paper. 

ACKNOWLEDGMENT. 

The  writer  takes  pleasure  in  thanking  the  owners  and  operators  of 
mining  properties  for  the  courteous  and  hospitable  reception  given  him, 
and  the  keen  interest  shown  in  the  subject.  Their  co-operation  made 
it  possible  to  obtain  many  details  which,  it  is  hoped,  will  make  the 
report  of  interest  to  the  practical  miner  and  the  prospector,  the  men  to 
whom  we  must  turn  at  last  for  aid  in  all  ventures  looking  to  the  develop- 
ment of  our  mineral  wealth. 

Special  thanks  are  also  due  to  Louis  M.  Prindle  and  Henry  G. 
Ferguson,  geologists  of  the  United  States  Geological  Survey,  with  whom 
the  writer  co-operated  in  much  of  the  field  work.  The  cordial  friend- 
ship and  active  assistance  given  by  these  gentlemen  did  much  to  make 
the  season's  work  pleasant  and  successful. 

Properties,   Uses,  and  World  Supply  of  Platinum   Metals. 

Platinum  with  a  hardness  of  4  to  4.5  and  specific  gravity  of  21.5, 
never  occurs  pure  in  nature,  being  alloyed  with  varying  percentages  of 
osmium  and  iridium  and  smaller  amounts  of  the  other  platinum  group 
metals,  of  gold,  of  iron  and  sometimes  copper  and  nickel.  The  typical 
modes  of  occurrence  in  California  show  it  associated  with  considerable 
amounts  of  the  first  two  metals,  traces  of  palladium  and  rliodium,  and 
one  or  two  per  cent  of  gold,  Avith  iron  in  such  subordinate  quantity  that 
the  crude  platinum  seldom  responds  to  the  magnet.  Analyses  of 
California  platinum  made  years  ago  by  Deville  and  Debray  liave  been 
widely  quoted  and  are  still  published  as  representative.  They  give 
85%  of  platinum  as  the  content  of  typical  California  crude  platinum. 
As  far  as  the  writer  knows,  there  is  only  one  occurrence  where  such  a 
high  grade  product  is  obtained  in  this  state.  Two-thirds  or  more  of 
the  crude  platinum  marketed  from  this  state  will  not  carry  over  65% 
platinum. 

Its  insolubility  in  acids,  its  malleability  and  ductility,  its  coefficient 
of  expansion  (nearly  equal  to  that  of  glass)  and  its  high  melting  point 
(1791°   C)    are  qualities  which  make  platinum  hard  to   replace,  and 


12  CALIFORNIA   STATE    MINING   BUREAU. 

indispensable  for  many  nrgent  uses.  Among  these  are  the  manufacture 
of  chemical  and  physical  apparatus,  in  the  oxidation  process  for  the 
manufacture  of  nitric  acid  from  ammonia,  in  magneto  points  and  other 
electrical  apparatus,  and  as  a  catalyzer  in  the  manufacture  of  sulphuri(3 
acid,  expediting  the  interaction  of  the  chemicals  without  itself  being 
consumed. 

G.  F.  Kunz^  estimated  that  the  world's  supply  of  platinum  in  1917 
was  about  4,000,000  ounces,  with  100,000  ounces  of  other  platinum- 
group  metals.  Kunz  divides  this  as  follows,  with  regard  to  the 
principal  uses  to  which  it  was  put : 

Catalyzing 400,000  ounces 

Dental    1,000.000  ounces 

Chemical  and  physical  apparatus 1,000,000  ounces 

Electrical  devices  500.000  ounces 

Jeweh-y    500,000  ounces 

Of  the  world's  total,  he  considered  there  were  1,000,000  ounces  in  the 
United  States,  of  which  200,000  ounces  were  used  for  catalyzing,  an 
amount  equal  to  that  used  by  England,  France  and  Germany  for  this 
purpose.  Of  the  remainder,  a  large  part  of  that  used  in  dentistry  is 
permanentlj'-  withdrawn.  An  increasing  amount  of  that  used  in  elec- 
trical Avork  is  going  back  into  trade  channels  as  scrap  metal,  instead  of 
going  to  the  junk  pile  with  worn-out  equipment.  The  metal  required 
in  catalyzing  and  in  laboratory'  equipment  is  used  over  and  over,  very 
little  of  it  being  lost.  The  increased  amounts  required  in  these  lines  is 
because  of  the  enormoiLS  expansion  of  business  made  necessary  by  the 
war.  In  the  face  of  such  need,  no  one  can  justify  the  use  of  platinum 
in  dentistry  or  jewelry  where  other  metals  can  be  made  to  serve. 

Iridium  is  superior  in  hardness  and  specific  gravity  to  platinum,  and 
at  present  commands  a  higher  price.  Its  complete  separation  from 
osmium  is  a  slow  and  expensive  process  and  is  a  task  avoided  by  many 
refiners,  who  prefer  to  buy  the  alloyed  metals  as  osmiridium,  estimating 
the  relative  percentages  of  the  two.  When  sellers  insist  on  exact  returns 
for  iridium,  the  osmium  is  not  paid  for,  the  explanation  being  that  it 
is  lost  in  the  refining  process.  California  platinum  metals  run  from 
30%  to  90%  combined  osmium  and  iridium  and  in  some  localities, 
notably  along  the  American  River,  the  percentage  of  iridium  nearly 
equals  that  of  platinum.  (See  table  of  analyses).  This  metal  is  valu- 
able for  manufacturing  of  standard  weights  and  measures,  for  fine 
tools,  for  knife-edges  in  sensitive  balances,  and  for  tips  on  fountain 
pens.  Less  important  applications  are  for  use  as  coloring  in  photo- 
graphy and  ceramics,  and  in  jewelry.  Alloyed  with  platinum  (10% 
iridium  and  90%  platinum),  it  gives  a  hard  alloy  which  is  useful  in 
manufacturing  electrical  goods. 

^G.  F.  Kunz — Platinum  with  especial  reference  to  Central  America. 


PLATINUM   AND   ALLIED    METALS. 


13 


Plate  I  (a).  Photomicrograph  of  platinum  metals  from  Clear 
Creek,  Shasta  County.  Recovered  on  Gardella  dreagc. 
Typical  product  obtained  on  dredgers.  Principally  plati- 
num, with  osmiridium  in  very  subordinate  amount. 
Magnified  30  diameters.  The  black  grain  is  gold.  Photo- 
micrograph  by   S.    A.    Tibbetts. 


Plate  I  (b).  Platinum  metals  recovered  by  cleaning  bedrock 
of  hydraulic  mine  at  Sawyers  Bar,  on  a  bench  of  Salmon 
River,  Siskiyou  County.  This  material  assays  high  in 
osmiridium,  with  less  than  5  per  cent  platinum.  Note 
the  sharp,  unworn  character.  Sample  donated  by  Wm. 
Wike,  Sawyers  Bar.  Photomicrograph  by  S.  A.  Tib- 
betts.    Magnified  30  diameters. 


14  CALIFORNIA    STATE    MINING   BUREAU. 

Osmium  is  insoluble  in  acids  or  aqua  regia  and  is  practically  infusible. 
It  is  used  largeh"  as  osmiridium  in  pointing  pens  and  in  fine  tools,  and 
has  also  been  emploj^ed  in  a  certain  type  of  electric  lamp.  It  occurs  in 
rather  high  percentage  in  practically  all  California  crude  platinum,  and 
appears  to  be  alloyed  usually  with  iridium.  The  large  nuggets  of  the 
Trinity  and  New  River  districts  have  been  shown  to  consist  principally 
of  this  alloy,  bound  together  by  small  percentages  of  platinum  and 
soluble  iridium.  California  osmiridium  is  verj'  much  in  favor  for 
tipping  fountain  pens.  The  California  alloy  of  these  metals  occurs 
as  coarse  pieces,  larger  than  most  of  the  imported  material.  This  makes 
it  easier  to  work  up  and  grind,  it  being  desirable  to  get  pieces  which  can 
be  shaped  and  cut.  In  tipping  the  pen  the  piece  of  osmiridium  is 
soldered  on  the  pen,  and  is  then  dressed  and  split  on  a  fine  wheel  coated 
with  diamond  dust. 

None  of  the  other  platinum  group  metals  occur  in  California  deposits 
in  sufficient  quantity  to  be  commercially  important.  Traces  of  pal- 
ladium and  rhodium  have  been  noted  in  several  analyses. 

Geography. 

Two  distinct  areas  in  California  are  covered  by  this  report.  The  first 
is  the  northwest  portion  of  the  state,  comprising  Del  Norte,  Siskiyou, 
Humboldt  and  Trinity  counties.  The  streams  of  this  district  drain 
westward  directly  into  the  Pacific,  and  the  region  is  one  made  up  almost 
wholly  of  mountains.  Here  the  Coast  ranges  of  California  blend  with 
the  Klamath  and  Cascade  mountains  in  a  tangle  of  confused  chains 
lacking  entirely  the  orderly  arrangement  and  symmetry  of  the  Sierra 
Nevada.  The  other  area  includes  the  western  foothill  slope  of  the  Sierra 
Nevada,  from  upper  Sacramento  River  to  Merced  River,  particular 
attention  having  been  given  to  a  study  of  those  dredging  districts  which 
are  situated  on  every  river  where  the  stream  escapes  from  its  rocky 
mountain  caiion  and  spreads  out  over  the  fringes  of  the  great  valley, 
dropping  its  load  as  it  loses  velocity  and  forming  rich  placer  deposits. 
A  small  detached  area  on  the  Russian  River  watershed  in  Mendocino 
County  was  studied.  Some  work  was  also  done  on  Beegum  Creek,  on 
the  Shasta-Tehama  counties  line.  The  former  is  a  Coast  Range  locality ; 
the  latter  is  on  the  west  side  of  the  Sacramento  Valley.  ^ 

The  boundaries  of  the  northern  counties  are  determined  by  natural 
features.  Del  Norte  County  facing  the  Pacific,  comprises  practically 
the  entire  Smith  River  basin  and  is  bounded  on  the  east  by  the  high 
crest  of  the  Siskiyou  Mountains.  Smith  River  enters  the  ocean  about 
four  miles  south  of  the  Oregon  line,  and  the  Klamath  flows  into  the 
Pacific  about  the  same  distance  from  the  Humboldt  County  line. 

Siskiyou  County  west  of  the  railroad  includes  the  Klamath  River 
drainage.     The  present  report  deals  with  two  sections  of  this  extensive 


4 


C3  o 


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15 


bJ 


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0 

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3 

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u 

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u 


PLATINUM   AND   ALLIED    METALS.  15 

rea — the  main  Klamath  River  from  Somes  Bar  to  the  Southern  Pacitie 
iailroad,  and  the  Salmon  River  district.  Each  of  these  is  a  unit,  and 
ogether  they  include  all  the  platinum  producing  properties  of  the 
ounty. 

Trinity  County,  like  Del  Norte  and  Siskiyou,  consists  of  an  extensive 
iver  basin.  Trinity  River  drains  every  portion  of  it.  and  the  multi- 
ude  of  perennial  streams  make  this  a  good  county  for  the  placer  miner, 
^he  auriferous  gravels  here  have  proven  richer  and  more  extensive  than 
a  any  of  the  neighboring  counties.  The  zenith  of  hydraulic  mining 
as  been  passed  here  in  the  Weaverville  and  Junction  City  districts; 
\rge  quantities  of  equipment  lie  idle  and  valuable  water  rights  have 
ipsed,  while  in  other  regions,  notably  around  Douglas  City  and  near 
he  mouth  of  South  Fork,  there  are  extensive  and  valuable  gravel 
eposits  undeveloped  because  water  is  lacking.  Good  dredging  ground 
i  being  worked  along  the  upper  Trinity.  Platinum  production  is 
mited  to  the  vicinity  of  Junction  City  on  the  main  Trinity,  and  to  the 
egion  near  the  mouth  of  South  Fork  on  and  a  few  miles  east  of  the 
lumboldt  County  line. 

Humboldt  County  is  largely  a  lumbering  and  agricultural  territory. 
\vo  areas  are  covered  in  this  report,  one  on  Trinity  River  near  Willow 
■reek  postotifice,  and  the  other  on  the  Klamath  from  Weitchpec  to 
omes  Bar. 

Field  work  was  done  in  the  foothill  belt  on  the  west  slope  of  the 
ierra  Nevada,  in  the  dredging  fields  of  upper  Sacramento  River;  on 
Vather  River  at  Oroville,  on  the  Yuba  at  Marigold  and  Ilammonton, 
nd  on  the  American  at  Natoma.  Besides  these  larger  fields,  the 
'osunmes,  Mokelumne,  Calaveras,  Merced  and  Tuolumne  River  dredg- 
ig  districts  were  covered.  This  entire  district  is  a  unit  as  regards 
eography,  climate,  physiography  and  geology.  The  dredgable  ground 
n  each  river  begins  at  the  western  end  of  the  rocky  caiion  and  extends 
'estward  down  stream  till  values  fade  out  and  the  ground  becomes  too 
)w  grade  to  mine. 

lelief. 

Because  of  the  extensive  field  covered  in  this  report,  it  is  best  to 
iscuss  each  district  as  a  unit.  In  this  way  it  is  possible  to  obtain 
reater  coherence,  and  to  bring  each  region  more  vividly  to  the  reader  "s 
ttention.  In  a  general  waj-,  however,  it  may  be  said  that  the  eon- 
rolling  feature  of  northwestern  California's  relief  is  an  old  peneplain, 
amed  by  Diller  the  Klamath  peneplain,  and  described  in  his  excellent 
^ork,  "Topographic  Development  of  the  Klamath  Mountains."  This 
Id  peneplain  is  now  tilted  gently  westward,  and  the  modern  streams 
ave  deeply  dissected  it.     Remnants  of  the  ancient  surface  are  visible 


16  CALIFORNIA    STATE   MINING   BUREAU. 

at  many  places.  Larger  panoramas  of  mountain  ranges  bring  out' 
clearly  this  feature,  showing  striking  uniformity  of  elevation  along 
chains  of  peaks  whose  summits  once  formed  part  of  a  continuous  sur- 
face of  subdued  relief.  There  are  only  a  few  mountain  ranges  which 
stand  out  independently  of  this  peneplain.  Chief  among  thase  are 
the  Salmon  Mountains  in  Central  Siskiyou  County  and  the  Siskiyou  i 
]\Iountains  between  Del  Norte  and  Siskiyou  counties. 

Some  attempts  have  been  made  to  separate  the  mountains  of  this- 
region  into  different  systems.  The  Cascades,  between  the  Sierra  Nevada 
and  Coast  ranges,  are  east  of  the  district  being  considered.  The 
Klamath  and  Coast  ranges  can  be  separated  in  some  places  by  topo- 
graphic differences.  Rounded,  gently  sloping  hills,  devoid  of  timber 
and  separated  by  broad  shallow  valleys  carrying  tiny  streams  which 
fade  away  in  summer,  are  characteristic  Coast  Range  features.  Such 
topography  is  seen  in  Humboldt  Countj^  on  the  road  from  Korbel  over 
Bald  IMountain  toward  Willow  Creek.  North  and  east  of  that  divide 
the  term  Klamath  Mountains  lias  been  applied.  The  distinction 
between  the  two  systems  is  based  largely  on  geological  grounds. 
Topography  does  not  always  offer  a  dividing  line,  as  the  Klamath  type 
is  developed  at  places  in  the  Coast  Range  where  intrusive  and  meta- 
morphic  action  have  been  violent,  and  the  Coast  Range  type  is  in 
evidence  at  places  in  the  Klamath  Mountains  where  Cretaceous  and! 
Tertiary  sediments  are  preserved. 

As  has  often  been  remarked,  the  streams  of  this  section  show  a  nearly 
uniform  direction  of  flow  northwestward  in  their  lower  courses.     Eel,' 
Mad,  South  Fork  of  Trinity,  Klamath  and  Smith  rivers  exhibit  this 
characteristic  where  they  flow  parallel  to  the  strike  of  the  sedimentary 
formations  on  the  coast  side.     But  in  their  upper  portions  they  have 
carved  deep  caiions  through  the  metamorphic  rocks,  flowing  in  narrow, 
trenches  with  practically  no  level  land.     This  action  of  the  streams  has- 
made  Trinity  County  a  succession  of  canons  and  mountain  tops  except  i 
on  the  upper  reaches  of  the  main  river  and  on  the  Hayfork,  where  the 
country  takes  on  an  open,  gently  rolling  aspect  with  low  grade  streams. 
The  Klamath  between  Happy  Camp  and  the  mouth  of  the  Trinity  keeps 
to  a  deep  narrow  trench  3000  feet  below  the  flanking  mountains.     The 
only  flat  land  in  this  distance  is  the  Orleans  basin,  scarcely  a  square 
mile  in  area.     The  river  bars  and  terrace  deposits  in  this  section  are 
only  a  few  acres  each  in  area  at  most,  and  the  material  of  the  canon 
sides  stands  at  such  a  steep  angle  that  sliding  is  common. 

Climate,  rainfall  and  character  of  timber  growth  vary  greath'  on 
the  two  sides  of  the  mountains  which  mark  the  limit  of  ocean  influence. 
The  lower  courses  of  the  rivers  are  open  for  the  passage  of  moist  winds 
and  fogs,  and  the  rainfall  is  heavy.     This,  with  the  rich  soil  in  the  river 


PLATINUM   AND   ALLIED    METALS. 


17 


)ottom.s,  offers  ideal  conditions  for  the  majestic  redwoods  which  thrive 
n  western  Humboldt  County  and  in  the  Smith  River  basin  westward 
Toni  the  mouth  of  South  Fork  to  the  edge  of  the  sandy  coastal  plain, 
lain  in  this  section  may  set  in  heavily  in  September  and  is  apt  to  total 
iouble  that  received  east  of  the  mountains.  The  heav}'  vegetation 
•egulates  the  flow  of  water  so  well  that  streams  are  perennial  and  there 
s  an  abundance  of  springs.  Eastward  of  the  coastal  chain,  the  red- 
voods  disappear  and  Douglas  fir  is  the  commonest  conifer,  with  a  very 
:ew  sugar  pines  sometimes  found  in  small  clumps,  and  with  the  noble 
ir  occurring  in  the  higher  mountains  above  5000  feet.  The  bright 
med  madroiia  is  also  much  in  evidence.  Underbrush,  which  is  often 
mpenetrable  on  the  coast  side,  thins  out  somewhat,  but  travel  away 
:rom  the  beaten  trails  is  usually  neither  pleasant  nor  easy  except  in  the 
;erpentine  belts,  which  support  little  vegetation. 


PLATINUM  PRODUCTION  OF  CALIFORNIA. 

The  annual  production  and  value  of  platinum  metals  in  California 
jiuce  1887,  have  been  as  follows : 


Tear 


Ounces 


Valu* 


Tear 


Ounces        Value 


887 
888 
889 
890 
891 
892 
893 
894 
.895 
.896 
.897 
.898 
.899 
.900 
[901 
1902 
L903 


100 

500 

500 

600 

100 

80 

75 

100 

150 

162 

150 

300 

300 

400 

250 

39 

70 


$400 

2,000 

2,000 

2,500 

500 

440 

517 

600 

900 

944 

900 

1,800 

1,800 

2,500 

3,200 

468 

1.052 


1904 

1905 

1906 

1907 

1908 

1909 

1910 

1911 

1912 

1913 

1914 

1915 

1916 

1917 

1918 

Totals 


123 

20O 
91 
300 
706 
416 
337 
511 
603 
368 
463 
667 
886 
610 
571 


10,722 


$1,849 

3,320 

1,647 

6,255 

13,414 

10,400 

8,386 

14,873 

19,731 

17,738 

14,816 

21,149 

42,642 

43,719 

42,788 


$285,248 


2—46903 


18 


CALIFORNIA    STATE    MINING   BUREAU. 


DREDGING. 


INTRODUCTION. 

The  annual  production  of  platinum  metals  from  dredging  operations 
in  California  is  so  small  compared  to  the  gold  yield,  that  it  is  overlooked 
by  the  ordinary  observer.  Nevertheless,  dredgers  produce  the  principal 
portion  of  the  annual  recovery  of  these  metals.  This,  of  course,  is 
because  of  immense  yardages  handled,  as  a  study  of  the  dredging  fields 
shows  clearly  wliat  is  meant  "when  we  speak  of  platinum  as  a  'rare 
metal.'  The  metals  of  the  platinum  group  are  produced  in  California 
only  where  gold  can  be  mined  at  a  profit.  Therefore,  in  discussing 
their  occurrence  and  the  possibilities  of  their  future  production  in  this 
state,  a  good  deal  of  space  has  to  be  given  to  the  subject  of  gold  placers 
if  any  intelligent  conclusion  is  to  be  reached. 

A  survey  of  our  dredging  fields  shows  a  remarkable  uniformity  in 
practice  and  equipment.  Close-connected  buckets  and  revolving 
screens  have  everywhere  replaced  open-link  buckets  and  shaking  screens. 
Electricity  is  used  exclusively  for  power,  costing  from  3/4^'  to  Ijf;  a 
kilowatt  hour.  From  the  time  the  bucket  line  dumps  its  load,  till  the 
final  cleanup,  gold-saving  methods  vary  only  in  the  degree  of  care 
exercised.  The  fine  material  passes  over  riifle  tables  of  standard  grade 
and  type.     Fine  tailing  goes  directly  to  the  pond  by  sluices,  and  coarse 


Photo   No.    1.      Dredge     No.     16,     Hammonton.      Equipped     with    2     stackers    to     comply    with 

regulations   requiring   a   clear   channel. 


PLATINUM   AND   ALLIED   METALS.  19 

ocks  wliieli  have  travelled  inside  the  screen  pass  from  its  lower  end 
into  a  belt  conveyor  which  elevates  and  stacks  them.  The  problem  of 
ailings  disposal  has  been  responsible  for  the  chief  variations  from  the 
tandard.  Boats  working  in  stream  channels  on  or  tributary  to  navi- 
gable rivers  are  amenable  to  debris  legislation,  and  are  required  to 
eave  a  clear  channel.  To  do  this,  double  stackers  are  used,  one  dump- 
ng  to  eaeh  side,  leaving  an  open  lane  between.  One  such  dredger 
s  in  operation  on  the  Yuba  River,  and  one  on  the  Calaveras.  Another 
'^ariation  is  the  resoiling  dredger,  on  which  the  long  belt  conveyor 
taeker  is  replaced  by  two  very  short  ones,  which  dump  coarse  rocks 
lear  the  boat  and  spread  them  more  uniformly.  The  fine  tailing  is 
arried  back  farther  than  usual  in  long  sluices,  so  that  it  spreads  over 
he  coarser  boulders  and  approximates  original  conditions.  Such 
Iredgers  were  designed  to  meet  the  complaints  of  those  who  objected 
o  the  destruction  of  farming  land.  Several  are  in  use  near  Fair  Oaks. 
The  Neill  jig,  first  introduced  on  the  Yosemite  dredger,  has  more 
ecently  been  installed  on  boats  near  Natoma,  to  recover  rusty  gold. 
]]aeh  of  six  dredgers  there  are  fitted  with  ten  jigs,  five  on  a  side,  with 
t  Hardinge  Mill  on  each  side  to  grind  the  sand  preliminary  to  jigging, 
rhis  installation  costs  about  $12,000  on  each  boat  and  requires  the 
erviees  of  an  extra  man. 

^respecting   Ground  for   Dredging. 

Shafts  give  more  reliable  results  than  the  Keystone  drill,  but  the 
atter  has  been  used  universally  where  shaft  sinking  was  impracticable. 
Misleading  returns  with  the  drill  may  be  due  to  (1)  careless  drilling, 
2)  spotted  ground,  or  (3)  hard  or  uneven  bedrock,  from- which  the 
Iredger  can  not  recover  all  the  values.  The  drill,  in  a  new  unprospected 
ield,  is  probably  as  useful  for  the  light  which  it  throws  on  conditions 
mderground,  as  for  the  indication  of  values.  Results  near  Hammon- 
on  are  said  to  average  80%  of  drill  indications.  Great  care  is  taken 
here  to  prevent  pumping  below  the  casing  when  drilling. 

At  ^Marigold,  squares  of  200  feet  are  drilled  at  a  cost  of  $2  a  foot. 
i  rocker  six  feet  long  is  carried  with  the  drill  rig  and  the  sand  from 
'ach  foot  of  drill  hole  is  pumped  and  washed  separately.  The  size  and 
lumber  of  gold  colors  is  noted  and  recorded  for  each  foot.  No.  1  size 
s  smallest.  No.  2  about  the  size  of  a  pinhead  and  No.  3  the  largest, 
rhe  total  gold  content  for  the  entire  depth  is  found  by  actual  recovery 
»id  weighing  and  not  by  fire  assaying.  Special  care  has  to  be  exercised 
vhen  drilling  through  the  pay  streaks. 

Prospecting  with  shafts  was  going  on  in  the  terrace  gravel  above 
I/'alaveras  River  near  Jenny  Lind  in  November,  1917.  C.  F.  Hellman 
)f  the  Butte  Dredging  Company  has  a  novel  washer  to  replace  the 
)rdinary  rocker.     The  latter  can  not  be  used  because  the  upper  ground 


20  CALIFORNIA   STATE   MINING   BUREAU. 

is  priucipally  stiff  claj^  The  dirt  from  the  shaft  is  shovelled  into  a 
pipe  20  feet  long  by  one  foot  in  diameter,  which  has  a  grade  of  one-half 
inch  to  a  foot  and  turns  20  times  a  minnte.  Water  plays  into  the  pipe 
and  helps  loosen  the  clay  which  is  given  a  rotating  motion  by  longi- 
tudinal strips  in  the  pipe.  The  cylinder  discharges  into  a  tray  10'  x  5' 
where  the  dirt  is  washed  and  puddled  till  throughly  broken  up.  From 
here  the  dirt  is  scraped  into  a  long-tom  rocker  8'x  1',  which  moves, 
through  a  six-inch  stroke  110  times  a  minute.  The  bottom  of  thej 
rocker  bed  is  covered  by  riffles,  followed  by  cocoa  matting  under  screen. 
The  cylinder  and  rocker  are  both  operated  by  a  l|-horsepower  motor.' 
A  ton  of  sticky  clay  gravel  can  be  washed  in  five  hours. 

FEATHER  RIVER  DISTRICT. 

This  was  the  pioneer  dredging  field  of  California  and  here  were 
worked  out  the  steps  which  had  to  be  taken  between  the  building  of 
the  early  Risdon  dredges  and  the  perfection  of  the  modern  steel-hulled 
giants  with  buckets  of  18  cubic  feet  capacity.  The  total  area  of  dredg- 
able  ground  in  the  Oroville  district  was  6450  acres.  This  took  in  part 
of  Oroville  townsite  and  extended  southward  along  the  Feather  River 
about  seven  miles,  with  an  average  width  over  one  mile.  Besides  this, 
there  were  smaller  adjacent  areas  on  streams  tributary  to  the  Feather. 
Wyman's  Ravine  District,  four  miles  southeast  of  Oroville,  contained 
about  680  acres  and  Honcut  Creek  about  the  same  area.  In  1902-  there 
were  35  dredgers  being  operated  by  twelve  companias,  and  the  gold 
yield  that  year  was  over  three  million  dollars.  In  February,  1918, 
seven  boats  were  in  operation  and  only  four  companies  were  left  in 
the  field.  It  is  estimated  that  the  dredging  ground  in  the  district  will 
be  exhausted  within  two  years,  and  production  from  now  on  Avill 
decrease  rapidly.  One  dredger  Avas  shut  down  in  October  1917,  one 
discontinued  work  in  January,  1918,  and  two  others  are  expected  to 
be  out  of  commission  within  twelve  months.  There  remains  after  that, 
the  possibility  that  some  of  the  ground  may  be  redredged,  but  at  the 
present  time  the  feasibility  of  this  is  entertained  by  very  few,  and  no 
plans  looking  to  such  work  have  been  made  so  far  as  known,  except  by 
Natomas  Consolidated  of  California. 

Some  of  the  ground  around  Oroville  has  proven  very  rich,  and  early 
profits  from  dredging  led  to  the  payment  of  nearly  any  price  for  land. 
One  company  paid  $1,500  an  acre  and  some  property  is  said  to  have 
brought  as  high  as  $3,000  an  acre.  Portions  of  the  townsite  have  been 
dredged  and  subsequently  graded  for  use  as  building  lots. 

Ground  has  been  drilled  to  a  depth  of  500  feet  in  this  district  without 
striking  true  bedrock.     The  last  bedrock  as  one  descends  the  river  is  at 


^California  State  Mining  Bureau,  Bull.  No.  57,  Gold  Dredging  in  California. 


■;:».i.i;V  'v 


PLATINUM   AND   ALLIED    METALS.  21 

;he  bridge  outside  Oroville.  from  whieli  point  the  waters  have  spread 
3ver  the  plain.  A  typical  section  of  dredging  ground  shows  a  top 
layer  of  6  to  16  feet  of  fine  soil,  followed  by  the  pay  gravel  with  a 
^Jepth  of  20  to  50  feet.  Thi.s  rests  on  a  bed  of  greyish  volcanic  ash, 
6  to  8  feet  deep,  which  forms  tlie  bedrock  for  dredging  operations.  It 
seems  to  be  the  consensus  of  opinion  that  the  gravel  below  the  ash  is  not 
pay  gravel.  Values  as  a  rule  are  in  the  lower  portion  of  pay  gravel 
]ust  above  the  volcanic  ash. 

The  earlier  operations  were  carried  on  with  small  dredgers  which 
were  unable  to  reach  the  best  values  on  bedrock  in  some  cases,  so  that 
there  is  no  doubt  a  good  deal  of  pay  left  in  places  under  the  old  tailing 
piles.  It  is  this  possibility  which  raises  the  question  of  redredging. 
There  were  also  the  less  easily  located  losses  arising  from  the  failure 
of  the  winchmen  to  dig  to  bedrock,  Avhen  thej-  could  show  greater 
yardage  by  shallow  Avork.  This  practice  was  more  prevalent  ten  years 
ago  than  now.  While  it  could  not  be  counted  on  as  a  definite  factor 
in  considering  redredging,  it  would  serve  as  a  margin  of  safety.  Co.st 
per  yard  is  cut  down  by  the  large  up-to-date  dredgers,  recovery  is 
improved,  and  the  nature  of  the  dredged  ground  would  permit  increased 
capacit}',  with  proportionately  lower  unit  expense.  There  is  one  such 
large  dredger  now  in  the  district  and  it  is  the  writer's  judgment  that 
it  will  continue  work  for  .some  years  after  the  new  ground  is  exhausted. 

Xatomas  Consolidated  of  California  operates  two  dredgers,  one  witli 
15  cubic  foot  buckets  and  one  having  7|  cubic  foot  buckets.  They 
recover  widely  varying  quantities  of  platinum  from  year  to  year  as  the 
platinum  content  of  the  ground  varies  directly  with  the  gold  values. 
The  platinum  is  fine  and  high  grade.  An  assay  of  a  recent  shipment  of 
several  ounces  showed  68.3%  platinum  and  20.53%  osmiridium.  This 
company's  production  of  precious  metals  will  decrease  about  25%  in 
1918  because  of  the  retirement  of  one  dredger. 

Oroville  Dredge  Limited  operated  two  dredgers  near  Thermalito. 
They  were  both  equipped  A\ith  7-i-  cubic  foot  buckets  and  dug  20,000  to 
30,000  cubic  yards  each  a  week.  The  ground  is  shallow  and  the 
dredgers  dug  to  a  depth  of  26  feet.  The  platinum  production  over  a 
period  of  two  years  has  averaged  one  ounce  for  160,000  cubic  yards 
of  ground  dredged.  This  gravel  was  low  grade  in  both  gold  and 
platinum,  being  situated  quite  a  distance  from  the  main  channel  and 
on  high  ground.     This  company  finished  its  ground  late  in  1918. 

The  Pacific  Gold  Dredging  Company  has  one  dredger  on  the  Feather 
River  seven  miles  below  Oroville.  This  boat  handles  140,000  cubic 
yards  of  ground  a  month  and  produces  less  platinum  than  is  recovered 
by  the  dredgers  in  the  upper  part  of  the  field;  as  nearly  as  could  be 
learned  it  takes  considerably  over  225,000  cubic  yards  of  ground  to 


22  CALIFORNIA   STATE   MINING   BUREAU. 

give  a  recovery  of  one  ounce  of  platinum.  This  company  in  November, 
1917,  reported  enough  ground  to  keep  the  dredger  in  operation  two 
years. 

The  American  Gold  Dredging  Company  retired  a  dredger  in  August, 
1917,  and  began  operations  with  a  new  one,  the  A.  J.  Holton  No.  4, 
late  in  October,  1917.  They  have  250  acres  of  ground  on  the  river 
seven  miles  below  Oroville  and  estimate  that  about  one-half  of  it  is 
dredging  ground.  This  will  furnish  several  years  w^ork.  The  platinum 
production  is  the  same  as  obtained  from  the  ground  near  Thermalito. 

Lawrence  Gardella  has  been  operating  a  dredger  at  Kentucky  Ranch 
on  Honcut  Creek  ten  miles  southeast  of  Palermo.  He  has  paid  no 
attention  to  platinum  and  has  recovered  only  a  few  ounces  in  all.  The 
dredger  is  old,  and  the  ground  contains  some  big  boulders.  This 
dredger  is  not  apt  to  make  any  important  production  of  platinum  during 
the  short  span  of  activity  remaining  to  it,  as  the  clean-up  methods  used 
are  not  refined. 

Upper  Feather  River. 

The  Feather  River  in  its  upper  course,  drains  large  areas  of  serpen- 
tine, amphibolite  and  granite.  Wide  belts  of  serpentine  cross  the 
watershed  with  a  northwest  trend.  Chromite  deposits  occur  at  a  few 
places,  but  they  are  relatively  small,  and  production  has  been  on  a 
small  scale.  Neocene  and  Pleistocene  gravel  areas  lie  all  along  the  river 
from  the  higher  Sierras  to  the  Oroville  dredging  fields,  and  prominent 
among  them  are  some  large  lacustrine  deposits,  like  the  Meadow  Vallej' 
beds.  There  are  many  gravel  bars  along  the  river  which  are  of  more 
recent  origin.  These  bars,  and  the  courses  of  tributary  streams  which 
often  make  up  into  steep  caiions  and  drain  older  gravels,  are  mined  in 
a  small  way  by  a  number  of  'snipers,'  mostly  old  men  who  may  be  found 
working  alone  with  rockers  and  long  toms  in  summer,  all  the  way  from 
Oroville  to  the  high  mountains.  JNIany  of  them  save  platinum  and 
bring  it  into  Oroville  in  the  fall.  A  mining  man  of  that  place  who  has 
handled  a  good  deal  of  this  material,  estimates  that  there  is  annually 
produced  in  this  way  from  12  to  15  ounces  of  platinum  metals. 

There  is  some  placer  mining  on  a  larger  scale  on  the  upper  Feather, 
but  operations  are  hampered  by  lack  of  water  and  lack  of  grade.  There 
is  no  record  of  production  of  platinum  from  these  hydraulic  properties. 

Resume. 

The  production  of  platinum  will  decrease  from  now  on  in  the  dredging 
district  of  the  lower  Feather,  because  of  the  rapidly  approaching 
exhaustion  of  new  ground.  Redredging  will  not  produce  much 
platinum.  Production  for  1917  was  about  94  ounces  of  crude  metal, 
including  that  taken  out  by  small  placer  miners.     Four  dredgers  which 


PLATINUM   AND   ALLIED   METALS. 


23 


participated  in  this  production  have  ceased  operations  and  one,  (the 
largest  in  the  district)  is  worldng-  part  of  the  time  in  ground  dredged 
before.  It  seems,  therefore,  that  a  decrease  of  from  25%  to  50%  in 
the  production  of  gold  and  platinum  metals  in  this  field  may  be  looked 
for  in  1918. 


YUBA  RIVER  DISTRICT. 
This  district  is  on  the  river  from  the  point  where  it  issues  from  its 
canon  to  one  mile  west  of  Marigold  townsite,  about  seven  and  one-half 
miles.     The  width  dredged  averages  about  one  mile  but  there  is  partially 


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Detail    of   bucket   line,    Dredge    No.    14,    Hammonton.     Buckets   hold    17    cu.   ft. 
and  weigh  2  tons   each. 


proven  ground  back  from  the  river  which  will  give  a  total  width  of 
about  two  miles.  There  has  been  a  total  area  of  2000  acres  dredged  in 
this  field  to  the  end  of  1917,  and  there  remains  an  equal  area  of  proven 
ground.  Work  began  here  in  1903  under  the  direction  of  W.  P.  Ilani- 
mon  and  R.  D.  Evans,  whose  interests  were  taken  over  in  1905  by  the 
Ynba  Consolidated  Goldfields,  a  corporation  of  which  W.  P.  ITammon 
has  since  been  managing  director.  The  Marysville  Dredging  Com- 
pany began  operations  in  1906  and  the  Pacific  Gold  Dredging  Company 
obtained  some  laud  on  the  extreme  upper  end  of  the  field,  just  below 
the  mouth  of  the  canon,  and  began  dredging  in  1916. 

The  trend  in  this  field  has  been  toward  big  scale  operations  and  the 
holdings  are  mostly  in  the  hands  of  the  Yuba  Consolidated  Goldfields 
who  had  2800  acres  of  proven  ground,  and  the  Marysville  Dredging 


24  CALIFORNIA   STATE   MINING  BUREAU. 

Company  with  about  1000  acres  of  known  ground  controlled.  The 
maximum  annual  gold  yield  so  far  attained  was  in  1910  when  $3,172,476 
were  recovered  with  fifteen  boats  in  operation.  The  total  reported 
yield  to  the  end  of  1918  is  somewhat  in  excess  of  $36,000,000. 

Pioneer  work  in  the  Oroville  field  indicated  what  errors  should  be 
avoided,  and  the  nature  of  the  ground  itself  in  the  Yuba  River  District 
led  to  tlie  construction  of  l)oats  Avith  increased  yardage  and  depth 
capacity.  The  tendency  now  is  to  retire  the  smaller  boats,  with  7| 
cubic  foot  buckets,  and  standardize  on  boats  with  18  cubic  foot  buckets. 
There  were  operating  in  December,  1917,  in  the  Yuba  River  field  a 
total  of  eleven  dredgers.  Two  dredgers  witli  buckets  of  7|  cubic  foot 
capacity  have  recently''  been  retired  by  the  Yuba  Consolidated  and  their 
capacity  will  be  more  tlian  equalled  by  a  new  boat  with  18  cubic  foot 
buckets  which  began  operations  in  December,  1917.  Another  of  equal 
capacity  has  been  contracted  for.  This  company  is  using  three  boats 
with  7  cubic  foot  buckets  and  five  with  18  cubic  foot  buckets.  The 
]\Iarysville  Dredging  Company  operates  two  dredgers  with  9  cubic  foot 
buckets  and  one  with  16  cubic  foot  buckets,  but  the  rated  capacity  of 
this  latter  is  considerably  higher  than  the  large  boats  of  the  Yuba 
Consolidated.  The  Pacific  Gold  Dredging  Company  operates  one 
dredger  with  buckets  of  9  cubic  foot  capacity  and  with  a  digging  ladder 
capable  of  digging  70  feet  below  the  water  line.  All  the  dredgers  now 
working  in  the  Yuba  River  field  are  equipped  to  dig  from  68'  to  92' 
below  water  level. 

The  upper  portion  of  the  gravels  in  the  flood  channel,  to  a  depth 
of  40  feet,  consists  of  old  tailing  from  the  hydraulic  mines  operated  in 
years  past  on  the  upper  Yuba  Avatershed.  This  is  low  grade,  containing 
about  six  cents  a  yard  in  gold.  The  ground  varies  in  depth  from  45 
feet  on  the  fringes  of  the  lower  end  of  the  field  to  around  100  feet  on 
the  upper  end.  The  bedrock  under  the  pay-gravel  is  the  typical 
volcanic  ash  of  the  Sierras,  altered  and  consolidated  in  some  cases  by 
pressure.  As  in  the  Oroville  district,  drilling  has  not  revealed  the 
true  bedrock.  The  last  true  bedrock  outcrop  is  of  greenstone  on  the 
Yuba  Consolidated  land  near  the  river  at  Daguerre  Point.  The  river 
is  subject  to  sudden  floods  and  has  a  swift  current  in  winter.  While 
it  is  often  stated  that  values  are  not  concentrated  on  bedrock,  it  is 
nevertheless  the  case  that  when  digging  is  done  during  periods  of  flood, 
there  is  apt  to  be  considerable  loss  because  the  dredgers  are  floating 
too  high  to  dig  to  any  great  depth.  This  has  been  demonstrated  to  the 
satisfaction  of  the  operators.  Drillers  who  have  worked  in  the  district 
believe  there  are  two  pay  channels  south  of  the  present  river,  the  older 
of  which  runs  southwest.     Between  this  and  the  upper  channel,  which 


PLATINUM   AND   ALLIED   METALS.  25 

appears  to  trend  northwest,  there  is  a  poor  streak.  The  gravel  is 
generally  mediimi  to  fine,  with  nothing  in  it  to  render  digging  difficult, 
and  dredging  conditions  are  nearly  ideal.  Values  vary  markedly  in 
the  ditferent  sections  of  the  field.  The  richest  ground  of  course,  is  in 
the  up-stream  section  nearest  the  mouth  of  the  canon ;  but  the  ground 
is  excessively  deep  and  recovery  not  as  complete  as  desired.  Parts  of 
the  middle  portion  of  the  field  run  as  high  as  40^  a  yard,  with  an 
average  stated  to  be  about  16^.  From  here  values  taper  down  rather 
sharply  and  it  is  believed  that  there  is  little  if  any  dredgable  ground 
below  the  holdings  of  the  ]\Iarysville  Dredging  Company. 

Platinum  occurs  in  very  small  ratio  to  the  gold  content,  but  the 
total  platinum  production  in  the  field  is  large  because  of  the  immense 
yardage  handled.  One  ounce  of  platiniun  to  50,000  cubic  yards 
dredged  is  the  recovery  obtained  in  the  middle  part  of  the  field.  In  the 
lower  gi-ound,  the  platinum  values  decrease  more  rapidly  than  the  gold. 
About  380,000  yards  of  gravel  are  dredged  there  for  every  ounce  of 
platinum  recovered.  The  metal  is  all  very  fine  and  as  might  be 
expected,  is  high  in  platinum  and  low  in  osmium.  The  greater  portion 
of  the  assays  indicate  from  62%  to  69%  platinum  and  an  average  of 
15%  osmiridium.  Some  assays  tend  to  show  that  iridium  forms  most 
of  this  15%  and  prices  paid  for  the  osmiridium  are  nearly  twice  the 
value  of  osmium.  The  study  of  platinum  in  this  district  is  interesting 
from  the  standpoint  of  compari.son  with  other  platinum  fit4ds,  as 
regards  geological  relations  and  comparative  values  of  platinum 
recovered.  Platinum  has  been  noted  in  the  concentrates  at  several  of 
the  old  hydraulic  mining  districts  in  the  county  but  there  has  evidently 
never  been  any  production  of  it  from  these  sources,  except  in  one  case 
noted  elsewhere.  There  is  a  marked  ditferenee  between  the  relative 
amounts  recovered  on  the  Yuba  and  on  the  adjoining  Feather  and 
American  rivers.  Chromiferoas  serpentine  areas  are  prominent  on  the 
American  watershed  not  many  miles  above  Natoma.  where  platinum 
metals  are  found  in  much  greater  proportion  to  gold  than  on  the  Yuba. 

The  total  yardage  of  gravel  handled  annually  by  the  dredgers  now 
operating  in  the  Yuba  River  field  will  be  approximately  25,000,000 
cubic  yards  which  will  yield,  at  the  present  rate,  about  215  ounces  of 
crude  platinum  metals.  Of  this  total  there  will  be  125  ounces  of  pure 
platinum,  basing  the  estimate  on  actual  returns  for  a  portion  of  the 
current  year.     There  will  also  be  slightly  over  30  ounces  of  osmiridium. 

The  only  w^ays  in  wdiich  platinum  production  in  this  field  can  be 
increased  are  (1)  increased  j-ardage,  (2)  closer  saving  of  values  from 
the  black  sand  concentrate,  and  (3)  saving  values  now  lost  in  tailings. 
With  present  conditions  prevailing,  there  is  no  reason  to  expect  any 


26  CALIFORNIA   STATE   MINING   BUREAU. 

enlargement  of  operations.  One  large  dredger  contracted  for  will  do 
little  more  than  replace  the  two  smaller  boats  which  are  approaching 
the  end  of  their  usefulness.  Scarcity  of  steel  for  peaceful  purposes 
the  past  two  years  have  made  it  very  difficult  for  dredger  companies  to 
procure  even  large  repair  parts,  and  cost  and  scarcity  of  materials  of 
construction  and  skilled  labor,  alike  render  new  construction  imprac- 
ticable and  inadvisable  from  a  business  standpoint. 

As  regards  increased  recovery,  anything  that  could  save  even  a  part 
of  the  platinum  now  going  to  waste  would  give  appreciable  results  when 
applied  to  such  an  immense  tonnage.  The  Yuba  Consolidated  dredgers 
alone  produce  monthly  60  to  70  tons  of  a  concentrate  composed  prin- 
cipally of  black  sand,  which  is  the  residue  left  after  saving  the  amalgam 
in  the  long  toms.  The  treatment  applied  to  this  sand  for  the  recovery 
of  gold  and  platinum  is  taken  up  in  detail  under  the  head  of  Methods 
of  Recovery.  The  increased  value  of  platinum  will  no  doubt  cause 
more  care  everywhere  in  its  recovery.  In  applying  refined  methods 
of  saving  in  any  metallurgical  process,  a  point  arrives  where  the  incre- 
ment of  saviug  does  not  justify  the  increase  of  cost  necessary  to  attain 
it.  Such  a  case  arises  when  the  concentrates  cost  more  to  treat  than 
ihey  appear  to  contain.  The  company  mentioned  above  has  now  a 
system  of  treatment  which  seems  to  have  reached  this  point. 

The  only  record  of  recent  platinum  production  on  the  upper  Yuba 
is  of  a  small  recover}^  from  Tertiary  gravels  on  the  South  Yuba  water- 
shed near  Nevada  City.  An  Indian  had  been  doing  asse.ssment  work 
there  for  years  on  the  Illinois  Bar  and  Ah  ]\Ioon  claims  in  the  Blue  Tent 
district.  In  1911,  as  nearlj^  as  can  be  learned,  he  noticed  some  metal 
grains  in  the  gold  clean-up  which  excited  his  curiosity  and  an  assayer 
who  Avas  sought  for  advice  identified  them  as  platinum.  The  Indian's 
tribal  brethern  swore  him  to  secrecy,  which  he  kept  faithfully  for  five 
years,  not  even  advising  the  owner  of  the  small  quantities  of  platinum 
which  he  was  mining  and  selling  annuall3\  In  the  fall  of  1916,  John 
Barleycorn  unlocked  his  lips  in  the  hearing  of  a  local  reporter,  and  it 
developed  that  he  had  sold  $400  to  $500  worth  of  platinum.  This  is 
said  to  have  come  from  the  Blue  Tent  tunnel  and  must  have  been  the 
result  of  small  operations,  as  assessment  work  usually  implies  the  mini- 
mum legal  amount  of  labor.  This  showing  would  seem  to  justify  the 
hope  that  re-opening  of  hydraulic  mines  in  that  county  will  help 
platinum  production.  Arrangements  are  now  under  way  to  resume 
hydraulic  mining  on  this  property.  The  results  of  hydraulicking  this 
gravel  will  give  us  the  first  definite  idea  of  platinum  yield  to  be  expected 
from  Tertiary  Sierran  gravels,  as  the  owner  has  been  brought  to  a 
realization  of  the  necessitv  of  saving  the  metal. 


PLATINUM   AND   ALLIED   METALS.  27 

AMERICAN  RIVER. 
Lower  American  River  (Folsom-Natoma  District). 

The  dredgable  land  in  this  district  extends  from  the  old  Blue  Ravine 
placer  diggings,  six  miles  above  Folsom,  along  the  American  River  to 
nine  miles  below  Folsom,  and  is  three  miles  wide  in  places,  with 
virtually  all  the  good  ground  on  the  south  side  of  the  river.  Dredging 
is  carried  on  at  two  levels  in  old  terrace  gravels  of  the  American.  The 
ground  varies  in  depth  from  20  to  70  feet.  The  upper  portion  is  hard, 
tenacious  clay,  which  calls  for  heavy  digging  machinery  and  offers 
difficulties  not  met  with  in  dredging  the  loose  stream  gravels  of  Yuba 
and  Feather  rivers.  Water  has  to  be  pumped  into  the  ponds.  Rusty 
gold  is  common,  and  Neill  jigs  are  used  on  six  of  the  dredgers  to  recover 
it,  as  discussed  more  fully  elsewhere  under  Mining. 

The  pioneer  dredger  was  put  in  operation  in  this  field  in  April,  1899, 
by  the  Colorado-Pacific  Gold  Dredging  Company.  It  was  a  Risdon 
boat  with  3^  cubic  foot  buckets.  Four  companies  followed  and  worked 
till  January,  1909,  when  they  were  consolidated  under  the  corporation 
name  of  Natomas  Consolidated  of  California.  The  Ashburton  Mining 
Company  finished  its  ground  in  1913.  The  only  other  remaining  com- 
pany, the  Wilkes-Barre  Dredging  Company,  sold  its  dredger,  etc.,  to 
Natomas  Consolidated  in  March,  1916,  leaving  that  firm  alone  in 
the  field. 

Natomas  Consolidated  in  December,  1917,  was  operating  ten  dredgers 
in  this  field.  Three  have  buckets  of  15  cubic  foot  capacity  and  are 
each  rated  to  dig  200,000  cubic  yards  of  gravel  a  month  using  over 
1100  horsepower,  as  compared  with  the  same  company's  Feather 
No.  3,  a  15  cubic  foot  boat  which  digs  about  200,000  cubic  yards 
a  month  near  Oroville  and  is  stated  to  use  735  horsepower.  Two 
dredgers  are  equipped  with  13  cubic  foot  buckets  and  five  with  9  cubic 
foot  buckets.  Natomas  No.  2,  another  9  foot  boat,  is  being  rebuilt. 
The  bucket  lines  on  the  large  dredgers  carry  83  buckets  and  can  dig 
60  feet  below  water  level.  The  gross  gold  yield  of  Natomas  Con- 
solidated in  1917  was  $2,303,544,  of  which  probably  $1,700,000  came 
from  the  American  River  field.  In  the  past  year  27,106,000  cubic  yards 
were  dredged,  about  20,000,000  cubic  yards  of  which  came  from  this 
field.  The  company  claims  to  have  247,200,000  cubic  yards  of  proven 
ground  left,  or  enough  for  nine  years. 

Parts  of  this  field  are  rich  agricultural  land,  a  factor  which  has 
led  to  the  evolution  of  the  reclamation  dredger.  This  type  varies  from 
the  ordinary  dredger  principally  in  the  construction  of  the  machinery 
used  to  dispose  of  the  tailings.  The  coarse  tailing  is  dropped  near  the 
boat  from  short  stackers.  The  fine  tailing  from  the  gold  tables  goes 
farther  back  through  long  sluices  which  distribute  it  over  the  top  of 


28  CALIFORNIA    STATE   MINING   BUREAU, 

the  coarse  cobbles,  so  that  the  resulting  pile  is  left  at  nearly  the  same 
level  as  before  digging.  The  land,  if  originally  suited  for  agriculture, 
is  left  in  condition  such  that  it  is  easily  prepared  for  planting  trees 
and  vines.  The  company  has  large  fruit  land  holdings,  and  besides  the 
large  acreage  of  overflowed  lands  which  it  has  reclaimed  for  farming, 
it  is  also  planting  some  of  the  dredged  ground  from  which  precious 
metals  have  been  extracted. 

Platinum  metals  are  recovered  in  this  district  in  considerably  higher 
proportion  than  in  the  Yuba  River  field.  A  reference  to  the  geology^ 
of  the  American  River  watershed  constitutes  apparently  a  strong  argu- 
ment for  those  who  favor  the  theory  that  these  metals  in  California 
have  their  origin  in  basic  igneous  rocks,  and  particularly  in  chrom- 
iferous  serpentine.  Large  areas  of  serpentine  cross  the  watershed  in 
several  belts,  trending  slightly  west  of  north.  One  such  belt  extends, 
with  interruptions,  from  the  Cosumnes  River  through  Latrobe,  out- 
cropping again  on  Green  Spring  Creek  (on  the  South  Fork  of  American 
River  watershed)  for  several  miles.  Another,  a  mile  wide  and  three 
miles  long,  lies  a  mile  south  of  Salmon  Falls,  and  still  another  crosses 
the  South  Fork  and  runs  nearly  to  the  North  Fork  near  the  old  Zant- 
gratf  mine,  having  a  width  of  nearly  a  mile  and  a  length  of  four  miles. 
Farther  north  and  east  other  such  belts  occur  over  the  entire  watershed 
of  the  river.  Chromite  occurs  frequenth'  in  these  serpentine  areas 
and  is  being  mined  now  in  many  places,  notably  near  the  Zantgraff 
mine  in  El  Dorado  County,  and  in  the  vicinity  of  Iowa  Hill,  Butcher 
Ranch  and  Towle  in  Placer  County. 

The  tenor  of  the  crude  platinum  is  such  as  to  make  us  believe  that  it 
has  not  undergone  such  a  long  trip  from  its  source  or  been  subjected 
to  erosive  action  as  long  as  were  the  platinum  metals  of  the  Feather 
and  Yuba  livers.  The  average  of  five  assays  made  on  lots  of  from  30  to 
80  ounces  each,  shoM^ed  43.49%  platinum  and  three  of  these  showed 
22.57%,  23.13%  and  25.17%  iridium.  Osmium  was  not  paid  for  and 
the  percentage  of  it  was  not  shown.  The  loss,  less  about  10%  repre- 
senting dirt,  etc.,  or  about  30%,  is  undoubtedly  osmium.  The  material 
is  thus  seen  to  closely  resemble  in  character  the  Trinity  River  metals 
recovered  by  the  Valdor  dredger. 

There  is  a  meager  record  of  platinum  production  in  this  field,  and 
the  retirement  of  so  many  firms  makes  it  impossible  to  get  any  such 
statistics  for  years  past.  The  figures  available,  indicate  production  for 
only  a  few  years  past.  The  rate  of  production  in  1914,  1915  and  1916 
was  about  150  ounces  per  annum.  This  represents  the  product  from 
16,000,000  to  18,000,000  cubic  yards  of  gravel  moved.  One  company 
now  retired  from  the  field,  reports  35  ounces  of  platinum  from  7,000,000 


^U.  S.  G.  S.  Folio  No.  5,  Sacramento  Quadrangle. 


PIATINUM    AND   ALLIED   METALS.  29 

cubic  yards.  This  is  noticeably  liiyher  in  proportion  to  gold  yield 
than  recovery  from  the  Yuba  and  Feather  River  districts.  Natomas 
No.  7  dredger  which  worked  on  AVillow  Creek  back  of  the  Natoma 
shops,  is  said  to  have  recovered  as  high  as  one  ounce  platinum  for 
$1000  in  gold,  as  compared  with  .4  oz.  platinum  for  .$1000  in  gold  at 
Oroville,  and  less  from  the  Yuba  River. 

UPPER  AMERICAN  RIVER. 

This  section  of  the  stream  has  a  swift  current  and  is  subject  to 
sudden  and  severe  floods.  The  canons  of  the  North  and  Middle  forks 
are  narrow  and  the  streams  flow  on  rough  beds  of  hard  rock.  Dredging 
as  described  below  has  been  confined  to  river  bars  made  up  principally 
of  old  hydraulic  tailings  which  often  cover  virgin  areas  of  ground. 
The  chief  difficulties  in  dredging  are  the  rough  hard  bedrock  and  big 
boulders.  Above  Folsom  the  river  flows  through  a  canon  carved  in 
granodiorite.  The  contact  with  amphibolite  on  the  east  crosses  the 
river  two  miles  above  Rattlesnake  Bar.  A  small  area  in  the  grano- 
diorite near  Rattlesnake  Bridge,  was  dredged  several  years  ago  by 
Edward  Gaylord.  There  is  very  little  ground,  if  any,  that  could  be 
dredged  on  the  balance  of  the  stream  between  Rattlesnake  and  the 
forks  of  the  river.  Some  claims  are  being  held  with  the  expectation 
that  they  will  prove  dredgable,  but  the  acreage  is  too  small  to  justify 
construction  of  a  boat  and  the  bedrock  is  hard  and  rough. 

On  the  Middle  Fork,  a  dredger  with  3|  cubic  foot  buckets  has  been 
operated  intermittently  since  March,  1914,  b.y  the  El  Dorado  and 
Placer  Counties  Gold  Mining  and  Power  Company.  The  digging  is  in 
river  bars  composed  chiefly  of  old  tailings  covering  some  new  ground. 
The  Pacific  Gold  Dredging  Company  operated  a  larger  dredger  with 
7^  cubic  foot  buckets  just  down  stream  from  the  last  named  boat. 
After  over  four  years  successful  operation  they  are  at  present  (January, 
1918)  moving  this  dredger's  machinery  to  the  North  Fork  of  the  river, 
where  work  will  start  about  three  miles-  above  the  junction  of  the  North 
and  Middle  forks.  The  ground  which  has  been  worked  was  reported 
to  run  about  10^  a  yard  through  the  gravel,  but  the  slate  bedrock  was 
worth  several  times  that  wherever  it  could  be  reached.  Care  has  to  be 
taken  during  the  winter  storm  periods  to  keep  the  boats  out  of  the 
reach  of  the  current.  This  ground  yields  well  in  platinum  metals. 
The  last  run  on  new  ground  gave  one  ounce  and  a  half  a  month  for  the 
one  boat  and  the  assay  showed  the  content  of  iridium  practically  equal 
to  platinum,  with  a  trace  of  palladium  and  rhodium.  Platinum  was 
not  saved  here  till  quite  recently. 

There  is  a  great  deal  of  black  sand  in  this  stream  which  makes  the 
recovery  of  fine  gold  difficult.     The  bulk  of  the  gold  in  the  upper 


30  CALIFORNIA    STATE   MINING   BUREAU. 

gravel  is  in  flakes  thinner  than  paper  and  floats  readily  if  dropped  on  i 
water.  This  gold  comes  in  large  part  from  old  hydraulic  mines.  The 
upper  gravels  which  are  in  reach  of  the  current  are  sorted  and  washed 
during  high  water  and  the  shape  and  location  of  gravel  bars  is  con- 
stantly changing.  The  fine  gold  in  them  is  often  concentrated  in  rich 
streaks  in  coves  or  on  the  sides  of  bars.  These  streafe  run  as  high  as 
$2  a  yard  or  more.  The  reported  recovery  of  10^  a  yard  from  the 
gravel  dredged  represents,  no  doubt,  only  a  portion  of  total  gold 
content.  The  fine  flakes  also  appear  to  be  hard  to  amalgamate.  If 
tailings  from  rockers  or  sluices  are  panned  they  often  show  that  only 
60%  to  70%  of  the  values  are  being  saved.  The  statement  of  one 
dredging  man  who  has  been  familiar  Avitli  dredging  on  tlie  upper 
American  for  years,  is  that  the  bulk  of  the  concentrate  worked  will 
stop  on  a  30-mesh  screen.  But  much  of  the  fine  gold  is  so  small  that 
a  streak  of  it  gives  the  impression  of  a  smear  of  paint.  The  conclusion 
is  inevitable  that  a  large  percentage  of  this  escapes.  This  is  true  of 
the  platinum  in  greater  degree  than  of  the  gold,  because  the  former 
will  not  amalgamate,  and  is  uniformly  finer  than  the  gold.  The 
American  River  has  long  been  a  fertile  field  for  experimentation  with 
all  manner  of  'black  sand'  devices. 

COSUMNES  RIVER. 

There  is  a  small  area  of  dredging  ground  on  this  river  between 
Bridge  House  and  Michigan  Bar.  It  is  estimated  that  there  remains 
undredged  160  acres,  which  have  bt3n  drilled  and  proven  work- 
able, and  40  acres  of  this  have  been  bought  and  are  being  dredged. 
Farther  upstream,  near  Michigan  Bar,  a  small  acreage  has  been 
dredged.  The  boat  which  was  operated  there  was  floated  down  the 
river  and  began  work  two  miles  west  of  IMichigan  Bar  on  the  south 
side  of  the  river,  on  July  18,  1917. 

The  topography  is  subdued,  being  characterized  by  low  rolling  hills 
and  a  shallow  bedrock  which  rises  gently  from  the  river  southward, 
outcropping  near  the  county  road.  The  gravel  has  been  mined  a  great 
deal  in  this  vicinit}',  but  because  of  its  thinness  the  operations  have 
been  on  a  small  scale.  Where  dredging  is  going  on,  there  is  a  bank 
30  feet  high,  of  which  15  feet  is  a  barren  overburden  of  sticky  reddish 
clay.  This  bakes  to  a  hard  'adobe'  in  the  dry  season  and  makes  heavy 
digging.  It  is  softened  somewhat  by  running  streams  of  water  along 
the  face  of  the  cut.  The  gravel  is  found  to  be  very  'spotted'  because 
of  the  old  drifting  and  surface  mining,  but  is  stated  to  have  averaged 
10^  a  yard  for  the  past  j^ear. 

The  Indiana  Gold  Dredging  Company  is  the  only  operator  in  the 
field.      Their    dredge    contains    the    machinery    of    one    of    Oroville's 


PLATINUM   AND   ALLIED   METALS.  31 

oldest  boats.  It  has  chain  and  sprocket  wheel  drive  with  75  buckets  of 
4  cubic  feet  capacity.  It  can  dig  27  feet  below  water  and  is  stated  to 
have  a  capacity  of  60,000  3^ards  a  month,  but  considering  the  ground 
it  handles,  there  is  doubt  if  it  disposes  of  over  two-thirds  that  amount. 
Its  horsepower  rating  is  210.  Table  space  for  gold  saving  is  small. 
There  is  sufficient  ground  owned  by  the  company  to  keep  the  boat  busy 
two  years,  and  land  for  an  additional  year's  work  has  been  examined, 
though  not  yet  purchased.  Probabl.y  the  dredge  will  be  in  condition 
to  retire  by  the  end  of  the  three  years. 

No  definite  idea  of  the  exact  platinum  yield  of  the  present  oi)erations 
is  obtainable  as  the  ground  has  only  been  Avorked  since  July,  1917. 
Past  production  one  and  a  half  miles  upstream  was  at  the  rate  of 
12  ounces  a  year.  The  usual  long  tom  is  used  to  clean  up.  The  black 
sand  concentrate  remaining  in  the  long  tom  after  recovering  the  gold, 
is  panned  down  by  hand  and  is  sent  to  one  of  the  company's  other 
dredgers  for  final  recovery  of  the  platinum.  The  assay  indicates 
33.3%  platinum  and  41.97%  osmiridium,  of  which  about  one-half  is 
iridium. 

MOKELUMNE  RIVER. 

The  dredgable  land  on  this  river  extends  from  the  mouth  of  the 
canon,  four  miles  above  Comanche,  a  distance  of  nine  miles,  to  within 
four  miles  of  Clement.  The  gravel  is  from  6  to  35  feet  deep,  with  an 
average  depth  of  20  feet,  carries  a  heavy  overburden,  and  lies  on  the 
typical  lava-ash  'bedrock'  of  the  western  Sierra  slope.  There  is  a  total 
dredging  area  of  450  acres  which  will  furnish  work  for  the  three 
dredgers  in  the  field  for  four  years  longer.  Field  cost  per  yard  dredged 
iias  run  1^^  lower  than  for  the  same  company's  ground  in  the  Oroville 
district,  but  the  average  jdeld  for  the  total  yardage  handled  Ims  also 
been  considerably  lower. 

The  American  Dredging  Company,  formerly  The  Oro  Water.  Light 
and  Power  Company,  controls  all  the  ground  in  the  district  which  they 
consider  will  pay  to  dredge.  They  are  operating  three  dredgers  at 
present,  having  begun  in  1904  with  one.  At  Lancha  Plana,  the  upper 
end  of  the  field,  a  boat  with  buckets  of  6  cubic  foot  capacity  is  working. 
Another  of  similar  size,  and  one  with  9  cubic  foot  buckets,  operate  in 
the  middle  and  lower  portions  of  the  field  respectively.  The  smaller 
boats  handle  as  high  as  170,000  cubic  yards  a  month.  The  larger  one 
does  not  handle  a  proportionately  larger  yardage.  It  was  the  first 
dredger  commissioned  there  but  developments  have  shown  that  it  was 
not  as  well  adapted  to  the  shallow  ground  as  the  smaller  ones.  The 
dredgers  are  called  the  Comanche  No.  1,  2  and  3.  The  last  boat  was 
commissioned  November  1,  1916. 


32  CALIFORNIA   STATE   MINING   BUREAU. 

The  platinum  production  varies  with  the  gold  content  of  the  gravels, 
and  is  somewhat  lower  in  proportion  than  on  other  streams  to  the  north. 
An  assay  of  the  platinum  recovered  here  could  not  be  obtained.  The 
selling  price  of  $47  an  ounce,  as  against  $61  obtained  by  the  company 
at  the  same  time  from  the  same  buyer  for  Oroville  platinum,  which 
assays  about  68%  platinum,  would  indicate  the  platinum  content  to  be 
about  50%.  The  company  at  present  is  paying  more  attention  to  the 
recovery  of  platinum  metals,  and  the  production  in  1917  was  higher 
proportionately  than  in  1916.  Present  indications  are  that  annual 
production  will  be  20  to  25  ounces  during  the  next  four  years.  Exact 
figures  of  production  can  not  be  pu])lished  in  a  case  like  this,  as  there  is 
only  one  operator  in  the  field,  and  it  is  not  the  policy  of  the  State 
Mining  Bureau  to  reveal  exact  details  of  private  business  without  tliC 
express  permission  of  those  interested. 

CALAVERAS  RIVER. 

Dredging  near  Jenny  Lind  has  been  carried  on  in  the  bed  of  the 
Calaveras  River  and  on  tlie  river  terrace  lying  possibly  60  feet  above 
the  present  channel.  Considerable  ground  has  been  turned  over  along 
the  river  from  the  mouth  of  the  canon  to  the  center  of  Jenny  Lind 
townsite,  and  dredging  is  now  progressing  downstream  from  the  town. 
Dredgers  first  started  work  here  in  1903.  There  were  in  all  about  600 
acres  of  gravel  in  this  field,  of  which  the  major  portion  has  been  worked. 
Depth  to  bedrock  does  not  exceed  40  feet  probably  anywhere  in  the 
district  and  some  of  the  gravel  is  only  18'  to  20'  deep.  The  material 
in  the  river  is  loose  and  easily  dredged,  being  made  up  in  part  of  old 
hydraulic  tailing-s  covered  by  fine  sand.  This  ground  is  stated  to  run 
about  lOfS  a  yard.  Tlie  terrace  gravel  carries  an  overburden  of  as 
much  as  15  feet  of  'hardpan'  or  hard  tenacious  clay,  which  carries  no 
values,  and  with  the  small  dredger  used  had  to  be  blasted,  at  an  added 
cost  of  3^  to  4^^  a  yard.  There  remain  undredged  about  200  acres  of 
the  low  grade  river  gravel,  but  the  terrace  gravel  has  been  worked  out 
as  far  as  prospected. 

The  Calaveras  Dredging  Company  finished  its  ground  in  the  field 
and  retired  in  Maj',  1916.  El  Oro  Dredging  Company  has  a  dredger 
with  4  cubic  foot  buckets  which  is  now  on  the  terrace.  It  was  idle  and 
under  repairs  in  November,  1917.  The  company's  present  holdings 
are  about  worked  out,  but  there  is  a  chance  that  new  ground  will  be 
developed  as  the  result  of  prospecting  under  way.  The  gravel  on  this 
terrace  costs  lO^f*'  to  llf^  a  yard  to  work,  including  cost  of  blasting, 
according  to  the  statement  of  El  Oro's  superintendent,  Mr.  Hellman. 
Their  dredger  can  handle  35,000  cubic  yards  a  month  of  this  gravel. 
(This  company  has  retired  from  the  field  since  the  writer's  visit.) 


PLATINUM    AND   ALLIED   METALS.  33 

The  Isabel  Dredge,  Ivy  L.  Borden,  owner,  is  working  in  the  river 
gravels,  which  reach  a  maximum  depth  of  40  feet  and  are  easy  digging. 
The  dredge  was  commissioned  in  June,  1917,  an  older  ))oat  having 
been  retired  in  INIarch,  191G.  It  is  equipped  with  5  and  7  cubic  foot 
buckets,  and  digs  27  feet  below  the  water,  handling  ]  2:3,000  cubic  yards 
a  month.  There  are  two  tailing  stackers  to  comply  with  debris  regu- 
lations which  require  a  clear  channel.  It  is  possible  that  the  stackers 
may  later  be  shortened  and  sluices  lengthened  in  order  to  do  resoiling. 
The  ground  being  worked  by  this  dredger  includes  portions  of  that 
formerly  handled  by  the  Calaveras  dredge,  with  spots  of  new  ground 
covered  in  places  by  tailings,  and  bedrock  that  Avas  not  always  reached 
In'  the  smaller  dredge.  It  is  estimated  that  there  are  200  acres  which 
will  yield  about  lOf^  a  yard. 

The  platinum  production  in  this  field  is  unimportant  now.  The 
Borden  Company  formerly  saved  9  or  10  ounces  yearly  when  w^orking 
in  ground  that  averaged  20^  a  yard,  but  the  present  output  will  amount 
to  scarcely  one-third  that.  The  output  from  the  Butte  Dredging  Com- 
pany's ground  has  been  only  eight  ounces  in  five  years.  There  does 
not  appear  to  be  any  prospect  of  the  annual  output  amounting  to  more 
than  four  or  five  ounces  per  annum  for  the  few  years  life  left  in  the 
field. 

TUOLUMNE  RIVER. 
La  Grange  Gold  Dredging  Company  operates  a  dredge  with  7  cubic 
foot  buckets  near  La  Grange  on  Tuolumne  River.  The  ground  is  said 
to  average  35  feet  in  depth,  and  consists  of  rather  coarse  gravel  overlain 
by  8  feet  of  clay,  and  resting  on  a  soft  volcanic  ash  bedrock.  This 
company  makes  a  practice  of  saving  the  black  sand  and  concentrating 
it  on  a  Iluelsdonk  Submerged  Table  Concentrator  (see  under  INIetliods 
of  Recovery).  The  recovery  of  platinum  metals  here  for  given  yardage 
is  equal  to  that  at  Oroville.  The  company  estimates  they  have  enough 
ground  for  12  years'  more  work.  The  platinum  metals  sold  in  1917 
averaged  about  72%  platinum  and  18%  osmiridium. 

MERCED  RIVER. 
The  Yosemite  Gold  Dredging  and  ]\Iining  Company  operates  a  small 
dredge  near  Snelling  in  the  gravels  and  overflowed  land  of  ^Merced 
River.  From  the  standpoint  of  platinum  production,  this  company '.s 
work  is  of  especial  interest  because  of  the  experiments  which  have  been 
carried  on  lately  in  concentrating  the  tailings  and  thus  saving  platinum 
and  gold  which  have  heretofore  been  lost.  This  phase  of  the  subject 
IS  covered  fully  under  the  heading,  "Possibilities  of  Increasing  Plat- 
inum Production"  (see  page  105).  The  holdings  of  the  above  company 
comprise  400  acres  and  they  have  been  Avorking  since  1907.     The  ground 

3—46903 


34  CALIB^ORNtxY    STATE   MINING   BUREAU. 

is  thought  to  average  16.5f'  a  cubic  yard,  and  is  said  to  cost  6.5^'  a  cubic 
yard  to  work. 

Summary  of  Newer  Dredging  Fields  in  California. 
As  the  present  dredging  fields  are  being  worked  out,  exploration 
becomes  more  and  more  active,  recovery  is  improved,  and  ground  that 
was  turned  down  once  as  "too  low  grade  to  dredge,"  is  taken  up  again 
for  consideration.  California's  best  ground  is  either  being  dredged 
now,  or  is  under  control  of  dredging  companies.  No  areas  e(|ual  in  size 
or  as  well  ada])ted  to  dredging  as  the  Feather,  Yuba  and  American 
River  districts,  remain  in  the  state.  The  physiography  and  geology  of 
the  region  where  the  Sierra  foothills  merge  into  the  great  central  valley 
gave  ideal  conditions  for  this  clas.s  of  mining.  Escaping  from  their 
narrow  rocky  canons,  the  streams  have  spread  their  sediments  over  a 
broad  floor  of  soft  volcanic  material.  This  condition  is  not  duplicated 
on  the  rivers  in  northwestern  California,  which  have  rocky  canons 
through  most  of  their  courses.  There  are  some  small  isolated  areas 
on  many  of  California's  rivers  wliich  could  probably  be  dredged  at 
a  profit,  some  which  are  being  dredged  and  a  few  which  have  been 
investigated  and  rejected.  A  summary  of  these  with  such  mention 
of  operating  companies  as  will  throw  light  on  local  conditions,  is  per- 
haps desirable,  because  California 's  platinum  output  is  dependent  on 
the  development  of  gokl  placers. 

Trinity    River. 

Trinity  River  has  been  the  scene  of  most  exploration  and  exploitation 
in  the  northwest.  The  Pacific  Gold  Dredging  Company  installed  a 
dredge  on  upper  Coffee  Creek,  but  they  were  forced  to  abandon  this 
ground  on  account  of  the  heavy  rocks  and  depth  to  bedrock  and  have 
moved  their  dredger  farther  down  stream  to  near  Carrville.  This 
venture  was  a  gamble  and  the  dredger  was  ])ut  in  its  first  location  on 
the  chance  that  it  could  be  operated  in  spite  of  the  boulders,  as  the 
bedrock  is  rich.  There  is  considerable  ground  in  this  region  known 
to  be  rich  in  coarse  gold,  but  heavy  boulders  have  prevented  working 
it.* 

Near  Trinity  Center,  the  Alta  Bert  Dredging  Company  has  operated 
a  7^  cubic  foot  boat  since  1903.  The  Alta  Bert  Company  sold  to 
Estabrook  Gold  Dredging  Company  in  1916.  It  is  a  peculiarity  of 
these  northern  streams  that  they  are  often  aggraded  by  ponding  in 
their  upper  courses.  This  gives  rise  to  broad  flats  of  gravel  and 
alluvium.  Such  a  flat  surrounds  Trinity  Center  and  extends  down- 
stream some  miles.     This  company  has  met  with  success  and  has  a 


*It  Is  reported  that  operations  were  started  again  dui-ing  December,  1918.  The 
Yukon  Gold  is  operating  on  dredging  property  about  half  way  between  Carrville  and 
Trinity  Center. 


PLATINUM    AND    ALLIED    METALS.  35 

msiderable  reserve  of  ground.  I\Ir.  Walker,  superintendent,  advises 
ley  have  some  platinuDi  and  will  market  a  small  amount.  Other 
rms  have  investigated  the  territory,  but  have  not  installed  dredgers, 
ravel  is  15'  to  -40'  deep.  Oroville  Dredge,  Limited,  is  now  prospecting 
round  on  Stuarts  Fork  above  Lewiston  (June,  1913). 

Four  miles  above  Lewiston,  the  Trinity  Gold  Dredging  Company  has 
Jen  dredging  since  1912.  They  have  made  a  good  recovery  of  gold 
it  get  no  platinuuL  They  had  originally  900  acres  of  ground.  The 
ravel  is  loose  and  reaches  a  depth  of  40  feet,  with  a  slate  bedrock, 
etween  this  dredger  and  Douglas  City  there  is  a  large  acreage  of 
round  which  might  prove  susceptible  to  dredging  but  is  inactive  at 
re.sent.  As  far  as  known  it  has  not  been  drilled.  On  the  Trinity 
iver  upstream  from  Junction  City  about  two  miles,  there  is  an  area 
:  possibly  500  acres  of  land  now  being  farmed.  Avhich  might  prove 
)od  for  dredging.  It  has  not  been  drilled,  but  was  viewed  as  a  possi- 
lity  by  local  operators.  The  Valdor  Dredge  has  been  in  operation  on 
rinity  River  five  miles  below  Junction  City  since  November,  1916. 
he  total  proven  area  is  small,  only  7-1  acres,  but  adjacent  ground  will, 
)  doubt,  be  added  soon  to  this.  The  bed  of  the  river  and  gravel  bars 
id  alluvial  flats  are  being  dredged.  The  bedrock  is  limestone  and 
rpentine  and  the  gravel  has  an  average  depth  of  2-4  feet.  The 
'ound  embraces  old  placer  diggings  and  has  proven  spotted  and  full 
:  holes.  Otherwise  dredging  conditions  are  apparently  fair  and  an 
rerage  of  about  125.000  cubic  yards  a  month  has  been  handled.  This 
roperty,  as  mentioned  elsewhere,  is  the  largest  producer  of  platinum 
.  Trinity  County. 

The  Trinity  flows  in  a  l)ox  canon  most  of  the  way  from  North  Fork 

New  River.  About  three  miles  above  the  mouth  of  the  South  Fork 
1  the  main  Trinity,  a  dredging  company  drilled  some  bars  and  flats 
:  1916.  This  ground  was  rejected  because  it  was  said  to  be  too  deep 
ir  a  small  dredger  and  too  small  in  area  for  a  large  one.  The  Iloopa 
alley  Indian  Reservation  includes  several  thousand  acres  of  gravel 
id  to  average  25  feet  deep,  part  of  which  could  no  doubt  be  dredged, 

mining  were  allowed,  but  the  exploration  of  this  tract  is  out  of  the 
lestion  at  present. 

The  Hayfork  of  Trinity  is  aggi'aded  in  its  upper  course.  In  the 
cinity  of  Hayfork  town  there  is  a  broad  valley  of  possibly  10,000 
!res,  of  which  two-thirds  are  reported  to  t)e  gravel.  This  flat  has  been 
rospected  by  several  dredging  companies  but  none  have  attempted  to 
ork  it.  The  attitude  of  the  residents  is  not  particularly  favorable  to 
'edging,  as  they  fear  it  will  spoil  farm  lands  adjacent  to  the  stream, 
he  failure  of  the  companies  to  make  satisfactory  deals  with  owners, 
id  the  natural  disinclination  to  pioneer  in  an  untried  district,  have 


36  CALIFORNIA    STATE   MINING   BUREAU. 

probably  been  instrumental  in  retarding  developments.  The  tribu- 
taries of  the  Hayfork  supported  a  multitude  of  miners  at  one  time; 
about  3000  Chinese  are  said  to  have  worked  there.  As  mentioned  else- 
where, the  platinum  content  of  the  gravels  in  this  basin  was  very  high 
in  proportion  to  gold. 

Klamath    River. 

On  the  Klamath  River  there  appears  to  be   little  ground  fit  for 
dredging.     Below    AVeitehpee,    the    government    reserves    unalieuate(^ 
lands  for  the  Indians.     From  Weitehpec  to  Orleans  the  liver  caiioi] 
is  steep.     At  Orleans,  a  change  in  the  character  of  bedrock  and  in  the 
direction  of  the  river,  led  to  the  widening  of  the  canon.     The  town  oi 
Orleans  is  on  a  pleasant  flat  which  is  the  lowest  of  six  old  river  terraces 
formed  by  the  Klamath  in  its  canon  cutting.     The  highest  of  these 
terraces  is  850  feet  above  the  stream.     The  gravels  at  the  different 
levels  have  been  partially  hydraulicked  and  the  bed  of  the  river  has 
been  mined  with  profit.     Water  for  hydraulic  mining  being  scarce,  tht 
idea  of  dredging  the  flat  around  the  town  was  advanced.     The  grounc 
was  drilled  four  j'ears  ago  by  The  Oro  Water,  Light  and  Power  Coraj 
pany.     They  abandoned  it,  giving  cost  of  transportation  and  genera 
risks  of  pioneering  as  reasons.     The  flat,  together  with  several  hundree 
acres  of  adjacent  high  bench  gravels,  belongs  to  one  company,  and  thu 
desire   to   dispose   of   these   holdings   in   one   parcel  is  apt  to   retarc 
dredging  operations.     The  gravel  is  from  35'  to  55'  deep  and  lies  oi 
slaty  schist  bedrock  which  has  been  crushed  and  faulted  a  good  deal 
The  gravel  is  in  general  medium,  but  there  are  some  large  l)oulders 
The  floor  of  this  bench  averages  10'  or  12'  above  low  water  level.     Ther' 
are  a  few  detached  areas  near  Orleans  which  might  be  dredged  in  cod 
junction  with  this,  but  are  too  small  to  be  taken  alone.     Dredginj 
here  should  yield  considerable  platinum. 

From  Orleans  to  Happy  Camp  the  river  flows  across  the  strike  o 
the  formations  and  the  result  is  a  V-treuch  in  which  the  only  grave 
deposits  are  on  narrow  benches.  These  are  nowhere  large  enough  fo 
dredging  nor  are  they  suitable  for  it.  In  the  vicinity  of  Hamburg  Ba 
a  small  suction  dredger  was  operated  some  years  ago  without  succesf 
A  small  dredger  operates  irregularly  on  the  Klamath  near  Oak  Ba] 
but  is  not  reported  as  highh'  profitable. 

El  Oro  No.  3,  formerly  El  Oro  No.  1  dredger  of  Oroville,  is  operate 
near  Yreka  on  Greenhorn  Creek,  which  drains  into  the  Klamath  throng 
Yreka  Creek  and  Shasta  River.  This  ground  does  not  produce  an 
platinum ;  only  an  occasional  grain  of  it  is  observed.  The  grav< 
averages  18  feet  in  depth,  with  slate  and  'porphyry'  bedrock  and  rarel 
is  any  serpentine  encountered.  The  dredger  carries  89  buckets  (  a 
6  and  6^  cubic  foot  capacity  and  has  a  16-foot  extension  on  the  diggic  ^ 


PLATINUM   AND   ALLIED   METALS.  37 

adder  which  permits  digging  38  feet  below  water.  Tlie  gold  is  coarse 
ud  is  caught  on  the  first  four  tables.  There  is  a  short  supply  of 
rater  in  summer  in  spite  of  the  elevation  (about  3000  feet).  In 
winter  snow  and  freezing  cause  trouble,  and  a  28  horsepower  boiler  is 
sed  for  making  steam  to  keep  frost  from  the  stacker  belt.  This 
redger  has  an  area  three-fourths  of  a  mile  long  and  possibly  one-fourth 
f  a  mile  wide  remaining  to  work.     The  gold  yield  is  satisfactory. 

cott    River. 

The  Siskiyou  Dredging  Company  operates  a  dredge  on  ]McAdams 
Jreek,  a  tributary  of  Scott  River  near  Fort  Jones.  The  ground  here  is 
s  much  as  50  feet  deep  and  there  is  a  quartz  porphyry  bedrock.  This 
redge  gets  no  platinum. 

Two  small  dredgers  were  operated  for  a  time  near  Callahan  on  Scott 
'iver,  but  neither  one  was  a  success,  probably  because  they  were  too 
iiall  for  the  ground.  One  of  them  cost  $-45,000  and  cleaned  up  a  total 
f  $10,000  in  26  months.     No  platinum  recovery  was  reported. 

acramento   River. 

Some  dredging  has  been  done  along  this  stream  in  the  neighborhood 
I  Redding,  but  operations  have  been  on  a  small  scale,  and  the  region 
3mains  today  the  largest  undeveloped  dredgable  field  in  the  state, 
he  ground  is  generally  favorable  for  dredging,  running  from  20'  to  40' 
eep,  and  being  composed  of  medium-sized  clean  gravel  on  soft  volcanic 
5h  bedrock.  The  ground  along  some  of  the  tributaries  is  rich  bottom 
md,  valuable  for  farming,  so  that  in  some  cases  dredging  may  be 
revented  by  disinclination  to  destroy  such  sources  of  perpetual  income, 
itroduction  of  extensive  irrigation  systems  in  the  Upper  Sacramento 
alley  is  also  enhancing  the  value  of  farm  lands. 

In  the  vicinity  of  Redding  several  suction  dredges  were  tried  years 
?o  without  success.  Attempts  were  also  made  to  get  at  the  gold  on 
?drock  by  the  use  of  pneumatic  caissons,  but  apparently  no  satisfactory 
(Suits  were  obtained  in  this  way. 

Late  in  1917  the  American  Gold  Dredging  Company  took  an  option 
1  the  Menzel  Ranch,  which  lies  along  the  north  bank  of  the  Sacramento 
iver  opposite  Redding  and  just  outside  the  city  limits.  The  results  of 
"illing  this  property  were  so  encouraging  that  they  closed  their 
)tion  on  February  5,  1918,  the  price  reported  being  $80,000.  The 
mpany  will  begin  the  construction  of  a  new  dredger  at  once.  It  will 
ive  buckets  of  6  cubic  feet  capacity  and  will  be  designed  to  dig  40  feet 
'low  the  water  level.  The  property,  which  contains  1000  acres,  has 
)t  been  entirely  prospected,  but  enough  ground  has  so  far  been 
jveloped  to  keep  one  dredger  working  for  its  entire  life.  This  prop- 
ty,  like  the  ground  on  Clear  Creek,  had  been  previously  drilled  and 
jected  by  another  company. 


38 


CALIFORNIA    STATE   MINING   BUREAU. 


Clear  Creek. 

This  tributary  enter.s  the  Sacramento  a  .short  distance  below  Redding. 

William  De.silhorst^  did  pioneer  work  in  dredging  here.  lie  operated] 
a  .steam  scoop  for  several  years,  and  although  it  is  said  to  have  cost! 
20^  to  25^  a  cubic  yard,  profitable  results  were  obtained.  In  1906  the] 
Shasta  Dredging  Company  began  operations  and  continued  work  for] 
several  years  on  a  parcel  of  about  700  acres,  nine  miles  from  Redding. 
Subsecpiently  many  of  the  Oroville  dredging  companies  drilled  adjacent] 
areas  and  were  unanimous  in  rejecting  it. 

After  this  verdict  had  been  passed,  Lawrence  Gardella  took  hold  of; 
che  land,  did  a  little  prospecting  and  installed  a  dredger.  Results  have 
been  satisfactory  from  the  first.  Gardella  claims  to  be  working  this 
ground  at  about  one-half  the  cost  of  dredging  in  the  Feather  and  Yuba 
fields.  This  is  due  in  part  to  the  fact  that  he  maintains  no  head  office 
force,  and  in  part  to  the  exceptionally  favorable  ground.  The  gravel 
averages  about  20  feet  deep,  carries  no  large  boulders  and  is  ideal  for 
dredging.  The  entire  acreage  of  dredgable  land  on  the  stream  is  not 
definitely  known.  Gardella  states  he  has  enough  ground  to  keep  three 
small  dredgers  at  work  fifteen  years.  He  is  moving  the  machinery  of 
the  old  Oroville  Union  dredger  to  Clear  Creek,  and  is  also  bringing  in 
from  Placer  County  the  machinery  of  the  dredger  which  he  operated 
near  Gold  Hill,  and  which  was  closed  down  in  July,  1917.  Near 
Gardella 's  land,  which  is  seven  miles  from  Redding,  the  American  Gold 
Dredging  Company  holds  250  acres,  of  which  two-thirds  is  considered 
dredging  land.     This  field  is  said  to  average  about  lO^j-  a  yard  in  gold. 

So  far,  platinum  production  here  has  been  discouragingly  small,  due" 
no  doubt  in  large  part  to  lack  of  care  in  cleaning  up.     Only  about  3^ 
ounces  were  saved  in  a  year's  work.     Better  results  are  looked  for  when 
the  three  boats  are  at  work. 

Cottonwood  Creek. 

Cottonwood  Creek  enters  Sacramento  River  from  the  west,  forming 
the  county  line  between  Tehama  and  Shasta  Counties  and  receiving 
the  drainage  from  the  extensive  area  of  Cretaceous  rocks  on  the  Shasta- 
Trinity  divide.  The  Shasta  Dredging  Compan,y  operates  a  dredger  on 
the  stream  near  Cottonwood.  The  production  of  platinum  metals  here 
in  1917  was  small,  and  .sales  indicated  about  33%  platinum  and  50% 
iridium,  with  osmiridium  approximately  17%,  but  not  paid  for.  The 
operators  hope  to  increase  the  production  of  platinum  and  iridium  in 
1918. 


Butte  Creek. 

This  stream  enters  Sacramento  River  west  of  Marysville.     The  Pacific 
Gold  Dredging  Company  is  operating  a  dredger  on  this  creek  and  has 


^Mines  and  Mineral  Resources  of  Shasta  County,  Cal.  State  Min.  Bur.,  1915, 


PLATINUM    AND   ALLIED    METALS.  39 

enough  ground  left  to  keep  at  work  two  years  longer.  The  dredger 
handles  from  100,000  to  120,000  cubic  yards  a  montli.  Tlic  platinum 
yield  is  slightly  higher  than  in  the  Oroville  district  and  amounts  to 
about  eight  ounces  a  year.  The  El  Oro  Dredging  Company  has  enough 
ground  along  Butte  Creek  to  operate  a  6  or  7  cubic  foot  l)oat  for  four 
years,  but  the  present  high  costs  and  difficulties  attending  the  building 
of  a  dredger,  preclude  the  probability  of  operations  there  in  the  near 
future.     The  cost  of  dredging  on  Butte  Creek  is  placed  at  34^  a  yard. 

Bear  River. 

Two  small  Risdon  dredgers  were  installed  on  this  stream  near  Wheat- 
land in  1901^  but  the  ground  proved  too  heavy  for  them.  The  property 
came  into  the  hands  of  the  Oroville  Dredging  Company  in  1907  and 
a  boat  with  7  cubic  foot  buckets  and  able  to  dig  to  bedrock  was  built. 
They  operated  for  ten  month.s  at  a  cost  of  5.4^  a  yard  in  ground  that 
was  said  to  average  7^  a  yard.  The  property  was  abandoned  and  has 
been  idle  since.  There  were  about  1000  acres  originally  taken  for 
dredging.  The  ground  was  heavy  and  clayey  and  the  gravel  small  to 
medium,  averaging  40  feet  deep.  On  Bear  River  near  Colfax  there 
are  some  areas  of  gravel  thought  to  be  dredgable,  which  liave  not  been 
drilled.  This  ground  is  similar  in  character  to  that  which  has  been 
worked  on  the  upper  American  River.  It  is  largely  in  river  bars, 
covered  by  hydraulic  tailing.s  and  lying  on  a  slate  bedrock.  If  it  can 
be  worked,  it  ought  to  prove  good,  as  the  ground  mined  thereabouts  has 
paid  well. 

Other  Streams. 

In  the  Gold  Hill  District,  Placer  County,  a  dredger  was  operated  bj' 
Lawrence  Gardella  of  Oroville  for  about  two  and  a  half  years.  The 
ground  adjoins  Auburn  Ravine  and  consists  of  stream  gravels  and 
alluvial  deposits  which  have  been  worked  by  shallow  placer  mining 
in  the  past.  It  is  shallow  and  only  about  one-third  of  it  carries  pay. 
Gardella  quit  work  here  in  July,  1917,  because  returns  were  unsatis- 
factory, and  has  moved  the  dredger  to  Clear  Creek.  There  was  no 
})latinum  found  here. 

In  Yuba  County,  near  Sucker  Flat,  one-half  mile  north  of  Smarts- 
ville,  a  stock  company  undertook  some  years  ago  to  work  a  high  bank 
of  gravel  by  combined  hydraulicking  and  dredging.  They  were  going 
to  hydraulic  the  bank  which  is  210  feet  high,  then  scoop  up  the  broken 
ground  with  a  dredger,  and  store  the  tailings  with  an  aerial  tramway. 
A  big  slide  is  said  to  have  put  a  stop  to  operations  after  several  hun- 
dred thousand  dollars  had  been  invested.  A  stationary  dredger  with 
74  cubic  foot  buckets,  made  by  the  Yuba  Construction  Company  was 


^Bulletin  57,  California  State  Mining  Bureau,  p.  163. 


40  CALIFORNIA    STATE   MINING   BUREAU. 

installed,  as  well  as  other  expensive  equipment.  This  project  had 
apparently  been  abandoned  at  the  time  of  the  last  report.^ 

There  are  some  areas  of  ground  in  the  Sierras  which  have  been 
mentioned  from  time  to  time  as  dredging  possibilities,  but  have  not 
been  developed.  Among  these  are  the  holdings  of  the  IMountain  jMeadow 
Dredging  Company  of  Chicago,  who  proposed^  to  install  a  dredger  two 
years  ago.  Their  plans  have  evidently  failed  to  mature.  They  had 
3000  acres  in  the  IMountain  Meadow  region  in  Plumas  County.  These 
gravels,  which  are  at  a  low  elevation  near  the  present  streams,  are 
Quaternary  alluvial  deposits.  There  are  several  such,  including 
deposits  in  Indian  and  Genessee  valleys.  There  are  also  large  areas 
of  Tertiary  gravel  ten  to  fifteen  miles  southwest  of  Susanville,  on  the 
mountain  tops  at  elevations  of  5000  to  7000  feet^  Both  these  classes 
of  gravel  have  been  mined  with  profit.  Hydraulic  mining  on  the 
Quaternary  gravel  is  limited  by  lack  of  grade  in  the  lower  ground,  and 
on  the  higher  portions  of  the  Tertiary  deposits  it  is  difficult  to  get  any 
water  for  hj^draulicking. 

Three  milas  south  of  Bucks  Ranch,  and  23  miles  from  Quincy,  Plumas 
County,  the  Gold  Mountain  Hydraulic  and  Dredging  Company  of  Los 
Angeles  has  440  acres  of  land  which  has  been  hydraulicked  recently. 
This  ground  is  largely  silt  and  sand  with  some  quartz  gravel  on  slate 
bedrock.  The  last  reported  run  is  said  to  have  given  $4,800  from  7500 
yards  mined. 

There  are  other  areas  of  gravel  tributary  to  the  upper  waters  of  the 
Feather  River,  which  have  not  been  investigated  so  that  no  judgment  of 
their  availability  for  dredging  can  be  passed.  The  same  is  true  of  the 
upper  Yuba  above  Nevada  City,  and  of  other  rivers  of  the  Sierras. 
It  is  probable  that  exploration  for  new  dredging  fields  in  California  will 
turn  in  this  direction  and  no  doubt  some  small  deposits  will  be  opened. 

As  far  as  known  there  has  been  no  good  dredging  ground  revealed 
yet  in  Southern  California.  Two  companies  who  have  prospected 
deposits  there  recently,  one  near  Los  Angeles  and  another  in  San 
Bernardino  County,  were  both  disappointed.  Sandy  gravel  at  the  head 
of  Gold  Creek  Caiion,  east  of  San  Fernando,  has  been  prospected  some- 
what, as  has  also  similar  ground  in  Soledad  Canon,  north  of  Lang 
Station.  The  promoters  of  these  projects  planned  to  grind  the  sand 
and  gravel  in  ball  mills  and  extract  the  gold  and  platinum,  but  a])pa- 
rently  their  inability  to  finance  the  venture  led  to  its  abandonment  for 
the  time  being.     Both  localities  are  in  Los  Angeles  County. 


^Waring,  C.  A.  :  Cal.  State  Min.  Bur.,  Mines  and  Mineral  Resources  of  Yuba  County, 
1916. 

=MacBoyle.  E. :  Mines  and  Mineral  Resources  of  Plumas  County.  Cal.  State  Min. 
Bur.    (in   press). 

sDiller,  J.  S.  :  U.  S.  G.  S.  Bull.  353,  p.  116,  Geology  of  Taylorsville  Region. 


• 


PLATINUM    AND   AIJilED   METALS.  41 

SEA  BEACHES. 

Platinum  in  association  with  gold  has  been  identified  along  the  Cali- 
fornia coast  from  south  to  north/  but  in  general  there  has  been  no 
commercial  production  of  either  from  such  sources  except  in  the 
northern  l>each  mines  in  tlumboldt  and  Del  Norte  counties.  The 
recover}^  has  usually  been  insufficient  to  pay  wages.  Gold  and  platinum 
are  both  very  fine  and  hammered  to  the  thinnest  flakes.  Many  have 
held  the  opinion  that  a  big  plant,  capable  of  handling  large  tonnage, 
Avould  give  a  profit  from  these  sands.  Actual  results  have  not  sustained 
this  theory.  There  often  is  a  small  profit  pos.sible  from  washing  the 
superficial  layer  of  black  sand,  which  is  concentrated  in  bands  along 
the  beach  particularly  during  winter  storms  from  the  northwest.  The 
practice  of  gathering  this  sand  and  taking  it  beyond  the  reach  of  the 
tide  for  washing  in  long  torn  or  rocker,  proved  profitable  years  ago  in 
Humboldt  County  at  Upper  and  Lower  Gold  Bluffs  and  at  Big  Lagoon 
and  Little  River.  Beach  sands  were  also  w^orked  in  a  small  way  along 
the  coasts  of  Santa  Cruz  and  San  Mateo  counties.  About  1884,  there 
was  a  rush  of  beach  miners  to  Laguna  de  la  Merced,  on  the  coast  of 
San  Francisco  County,  and  for  a  time  200  men  were  attempting  to 
mine  gold  there.     A  very  fcAv  are  said  to  have  made  a  little  profit. 

Del   Norte  County. 

A  mile  south  of  Crescent  City,  Del  Norte  County,  a  beach  mine  was 
operated  in  the  90 's  by  one  Yates,-  who  employed  a  few  men  to  wash 
the  sands,  w^hich  were  run  over  a  series  of  plates.  "Working  on  this 
small  scale,  a  fair  return  was  reported.  The  most  ambitious  attempt 
ever  made  to  mine  beach  sands  in  California  for  gold  and  platinum 
was  launched  by  the  Oro  del  Norte  Company,  incorporated  for 
$1,000,000  by  Theodore  Heintz,  a  mining  engineer.  This  company  built 
a  plant  said  to  have  cost  over  $125,000,  on  the  beach  two  miles  south  of 
Crescent  City.  The  plant  and  the  process  used  are  described  in  the 
chapter  on  Mines  and  Mineral  Resources  of  Del  Norte  County,  Report 
of  State  IMineralogist  1913-14'.  It  took  this  company  a  considerable 
time  to  satisfy  themselves  that  the  values  they  could  save  would  not 
])ay  for  the  cost  of  extraction.  The  plant  operated  for  over  a  year, 
but  was  closed  down  in  1914  and  has  been  dismantled. 

Humboldt  County. 

Another  recent  installation  for  extracting  gold  and  platinum  values 
from  black  sands  is  at  Big  Lagoon  in  Humboldt  County.  This  lagoon 
contains  eight  to  nine  square  miles  of  brackish  water  and  is  separated 


'An  enumeration  would  include  practically  every  coast  county  in  the  state. 
-Cal.  State  Min.  Bur.,  Report  XII,  1894. 
=Also,  in  Report  XIV,  pp.   375-379. 


42  CALIFORNIA    STATE    MINING   BUREAU. 

from  the  ocean  by  a  sand  bar  one-half  mile  wide.     As  mentioned  above,j 
the  sands  here  have  been  washed  profitably  in  a  small  way.     The  Bi 
Lagoon  IMining  Company  has  a  barge  here  which  they  have  fitted  withj 
a  centrifugal  pump  for  raising  the  sand  from  the  bottom  of  the  lagoon 
Driftwood  and  coarse  material  is  removed  by  screening  to  20  mesh  an 
the  fine  sand  flows  over  a  double  set  of  wooden  riffles  to  give  a  richj 
concentrate.     The  equipment  can  handle  30  cubic  yards  of  sand  an 
hour  and  300  cubic  yards  are  required  to  give  one  ton  of  concentrate, 
at  a  cost  of  $15,  according  to  the  owners'  statements. 

An  assay  of  this  concentrate  tended  to  show  that  it  was  worth  $10 
a  ton,  with  a  content  of  two  and  one-half  ounces  of  gold  and  one-half 
ounce  platinum  a  ton.  This  would  mean  that  the  original  sand  carried 
33;?j^  a  yard.  Such  assays  as  this  are  of  little  value,  when  the  gold  and 
platinum  occur  as  'free'  metals  in  grains  and  flakas.  One  small  flake, 
more  or  less,  in  the  portion  assayed,  may  make  a  difference  of  as  much 
as  $20  a  ton  either  way  in  the  indicated  values,  depending  on  the  size 
of  the  sample  tested.  Every  assayer  is  familiar  with  the  difficulty  of 
assaying  quartz  rich  in  free  gold,  or  concentrates  carrying  'free'  values 
The  only  reliable  way  of  testing  this  sand  would  be  to  wash  quantities 
of  it  taken  from  different  depths,  in  long  toms  or  rockers. 

Results  of  work  done  on  beach  sands  indicate  that  the  main  body  of 
sand  in  depth  does  not  contain  values  enough  to  repay  mining.  Work- 
able sand  is  found  along  the  water-line  where  heavy  constituents  have 
been  concentrated  by  waves  and  wind.  This  concentration  has  been 
carried  to  such  an  advanced  point  that  the  rich  layer  of  beach  sand 
may  be  509^,  heavy  black  sand.  The  difficulty  of  extracting  the  values 
completely  from  this  is  readily  appreciated  when  we  consider  that  two 
or  three  per  cent  of  such  black  sand  in  an  auriferous  gravel  renders 
recovery  of  fine  values  practicaly  impossible,  and  has  led  to  the  failure 
of  many  companies.  It  becomes  necessary  to  remove  perhaps  1000 
pounds  of  this  material  from  each  ton  to  get  the  few  cents  in  gold  and 
platinum.  The  reverse  process,  or  removal  of  the  platinum  and  gold, 
would  be  preferable  if  commercially  applicable  to  such  low  grade 
material.  The  fancied  riches  to  be  obtained  from  mining  beach  sands 
on  a  big  scale  have  never  been  realized  yet,  and  there  appears  to  be 
no  equipment  applicable  to  this  class  of  ground  which  will  handle  a 
large  tonnage  at  a  profit. 

Laws  Affecting    Land    Under  Tide   Waters. 

In  connection  with  the  subject  of  beach  placers  a  short  statement  of 
the  law  regarding  ownership  of  lands  under  tide  waters  ought  to  be 
interesting.  The  following  extracts  are  taken  from  paragraph  429, 
Vol.  2.  Lindley  on  Mines : 

"Thei-e  is  no  principle  involved  in  the  consideration  of  the  public  land  system 
better  settled  or  more  clearly  enunciated  than  that  lands  under  tidal  waters  and 
below  the  line  of  ordinary  high  tide  are  not  public  lands.     *     *     *     Title  of  such  land 


PLATINUM    AND   ALLIED   METALS. 


43 


i.s  in  the  state  in  landlocked  bays  from  headland  to  headland  and  from  the  line  of 
ordinary  hiRh  tide  on  the  shore  of  the  open  ocean  seaward  to  the  distance  of  three 
miles  or  a  mai'ine  league. 

"Where  lands  of  this  character  form  part  of  the  territory  acQuirod  under  treaties 
of  cession  and  purchase  which  for  the  time  are  not  included  in  the  boundaries  of  any 
state  but  are  in  territories  or  insular  dependencies  with  the  temporarv  form  of  sov- 
einment.  *  *  *  the  United  States  holds  them  in  trust  for  tlie  benefit  of  such  states 
as  may  ultimately  be  carved  out  of  them.  It  has  been  the  policy  of  the  government 
to  leave  the  administration  and  disposition  of  the  sovei-eign  rights  in  navigable  waters 
and  in  the  soil  under  them,  to  the  control  of  the  states,  respectively,  when  organized 
and  admitted  into  the  Union.  At  the  same  time  the  Supreme  Court  of  the  United 
States  has  the  power  to  grant  such  title  to  soil  under  the  high-water  mark  of  tide 
waters.  A  mining  claim  can  not  be  so  located  as  to  extend  below  the  line  of  ordinary 
high  tide. 

"By  Act  of  March  25,  1909,  the  California  legislature  forbade  the  sale  of  land 
between  high-  and  low-water  mark,  and  over  which  the  tide  ebbs  and  Hows.  In 
the  case  of  oil  taken  from  such  land  below  high  tide  at  Summerland,  the  state  has 
not  interfered.  It  is  held,  however,  that  a  littoral  owner  may  bring  suit  to  abate  a 
nuisance  if  such  entrance  on  land  below  high  tide  should  result  in  obstructing  his 
passage  to  or  from  the  open  ocean." 

It  is  thus  seen  that  no  title  can  be  obtained  to  such  lands,  either  from 
the  state  or  federal  government.  The  operator  of  a  mining  enterprise 
in  sneh  a  location  is  liable  to  prosecution  by  the  United  States  if  he 
interferes  in  any  way  with  navigation,  or  he  may  be  liable  to  ejection 
bv  the  state  government. 


Analyses  of  California   Black  Sands. 

Prom  time  to  time  the  attention  of  mining  men  turns  to  the  problem 
of  our  black  sands  and  to  the  possibility  of  extracting  from  them  not 
only  the  precious  metals,  but  also  other  minerals  of  industrial  value. 
At  the  time  of  the  Lewis  and  Clark  Exposition  the  U.  S.  Geological 
Survey  carried  on  an  extensive  investigation  of  black  sands  of  the  entire 
Pacific  Slope.  The  following  analyses  of  heavy  black  sands  from 
representative  California  localities  are  taken  from  Bulletin  285,  U.  S. 
Geological  Survey.  All  these  except  one  are  beach  sands.  The  results 
shown  were  obtained  from  analyses  of  samples  taken  in  most  cases  by 
local  miners  under  varying  conditions,  and  probably  are  of  value  chiefly 
m  showing  the  relative  proportions  of  the  different  constituents,  rather 
than  absolute  quantities. 

Figures  represent  pounds  per  ton,  except  gold  and  platinum. 


is' 

I' 

3 

n 

O 

Q 
p 

3 

O 

o 

3 

N 

1 

O 

c 

B 

■    to 

g 

»  a 

Location 

1 
1 

I 

1 
1 
r 

3 

1 

Smith  Riv?r  (beach) 

840.6 

508.9 

8.3.3 

365.9 

17.45 

238 

12.45 

Gold    Bluff    

244.5 

75.2 

171.6 

818.6 

16.94 

593 

6.01 

Crcscsnt   City   

4S0.8 

100.4 

503.1 

574.2 

56.03 

43.55 

132 

0,24 

San   Mateo   County 

3r>6.6 

1022 

14.2 

2S0.0 

110 

215 

Trace 

Yuba    River    (Marysville) 

563 

122 

10.7 

176.0 

Trace 

3 

714 

0.97 

iNo  platinum. 


44  CALIFORNIA   STATE   MINING  BUREAU. 


OTHER  OCCURRENCES. 


MENDOCINO  COUNTY. 

An  interesting  occurrence  of  platinum  metals  in  this  couuty  was 
recently  brought  to  notice,  thirty-five  j^ears  after  the  last  miner  had 
ceased  work  on  the  property.  The  writer  spent  two  days  in  the  district, 
and  also  spent  a  few  hours  in  a  locality  about  twenty  miles  distant, 
where  there  is  a  similar  deposit  properly  to  be  considered  as  a  unit  with 
the  above. 

The  first  named  properly  is  about  two  miles  east  of  Hopland,  a  station 
on  the  Northwestern  Pacific  Railroad  100  miles  north  of  San  Francisco. 
About  1880  ]\Ir.  Howell,  proprietor  of  the  Duncan  Springs  Resort,  and 
a  partner,  worked  two  gulches  on  this  land  by  placer  mining  with 
rockers  and  sluices.  The  surviving  partner  reports  that  they  recovered 
about  $1500  in  gold  and  an  equal  weight  of  platinum  metals,  or  about 
15  ounces,  in  two  sea.sons.  Noting  the  recent  enhancement  in  value  of 
platinum,  this  man,  now  too  old  to  mine  the  ground,  called  it  to  the 
attention  of  Howell's  sons,  who  l)ought  256  acres,  embracing  the 
principal  part  of  the  deposit. 

The  section  in  question  forms  the  eastern  side  of  Russian  River 
Valley.  The  gravel  has  been  preserved  in  a  chain  of  rounded  hills 
which  trends  northwest  for  about  two  miles  in  accordance  with  the 
strike  of  the  principal  sedimentaries.  The  hills  reach  a  maximum  ele- 
vation of  860  feet,  which  is  373  feet  above  the  present  valley  floor  at 
Hopland  station.  McDowell  Creek,  flowing  into  Russian  River  from 
the  east,  has  cut  a  broad  valley  through  the  hills,  and  many  of  its  tribu- 
taries have  carved  gulches  in  the  deposit.  All  except  two  of  these  are 
simply  rainwater  gullies,  and  go  dry  immediately  after  a  storm.  The 
sections  exposed  by  these  gullies,  taken  in  connection  with  a  consider- 
ation of  the  rocks  enclosing  the  deposit,  give  a  good  idea  of  the  geo- 
logical conditions  just  preceding  and  accompanying  the  deposition  of 
the  pay  gravel. 

The  area  is  one  made  up  of  many  members  of  the  Franciscan  group. 
From  the  detritus  of  Franciscan  metamorphics  and  igneous  meml)ers 
a  thin  layer  of  gravel  carrying  gold  and  platinum  metals  has  been  laid 
down.  This  deposition  appears  to  have  occurred  in  Tertiary  time.  It 
is  covered  by  only  a  thin  layer  of  soil. 

On  the  southwest  side  of  the  deposit  reddish  Franciscan  jasper 
heavily  stained  by  manganese  oxides,  strikes  N.  55°  W.  and  dips  70°  W., 
forming  part  of  the  lioundary.  In  contact  irregularly  with  the  chert 
near  the  Burns  reservoir  and  surrounding  the  gravel  to  the  east  and 


PLATINUM    AND    ALLIED   METALS.  45 

southeast  are  various  outcrops  of  greenstone  showing  stringi-rs  of 
quartz.  Some  ehlorite-mica  schist  also  occurs  liere  and  one  gukth 
exposes  the  sandstone  which  is  so  prominent  to  the  eastward,  and  has 
furnished  material  for  the  underlying  gravel.  Farther  nortli,  along 
the  west  side  of  the  deposit,  occasional  small  outcrops  indicate  a 
boundary  of  igneous  and  metamorphic  rocks  with  the  greenstone  phase 
prominent.  About  midway  of  the  deposit  near  the  west  edge,  a  cross- 
cut tuunel  had  been  started  northeast  but  was  inaccessible.  East  of  it, 
part  way  up  the  hill,  a  shaft  had  lately  been  sunk  17  feet  and  a  hole 
from  the  bottom  of  this  was  bored  20  feet  deeper.  This  shaft  and 
boring  penetrated,  (1)  2  feet  of  red  soil;  (2)  1|  feet  of  yellow  clay; 
(3)  12  feet  of  gravel,  thinning  toward  the  west  and  carrying  no  pay; 
(i)  21  feet  of  clay  shale  dipping  20°  to  30°  NE.;  (5)  small  fragments 
of  a  hard  rock,  evidently  a  phase  of  the  igneous  rocks  to  the  west  and 
probably  the  west  rim-rock.  About  400  feet  northeast,  on  the  hill  top, 
a  shaft  has  been  sunk  86  feet.  This  passed  through  a  thin  layer  of  the 
auriferous  gravel  near  the  surface  but  for  the  balance  of  the  distance 
traversed  a  uniform  brownish  gravel  composed  entirely  of  pebbles  of 
the  sandstone.  This  sandstone  gravel  was  practically  barren  of  gold 
and  platinum. 

One  of  the  larger  gulches  on  the  northeast  side  empties  eastward  into 
a  branch  of  McDowell  Creek  and  has  cut  a  rather  deep  trench  across 
the  gravel,  giving  a  \  trough  with  a  hill  on  each  side.  The  banks 
show  a  considerable  thickness  of  the  last  described  sandstone  gravel 
with  occasional  small  lenses  of  light  colored  clay  and  some  darker  shale. 
This  series  shows  marked  uniformity  in  character  and  an  entire  absence 
of  igneous  and  metamorphic  rock  fragments.  At  the  head  of  this  gulch 
a  crosscut  tunnel  has  been  driven  southwest  170  feet,  presumably  in 
search  of  a  pay  streak.  This  crosscut  is  entirely  within  the  sandstone 
gravel.  The  pebbles  in  the  gravel  are  small  and  all  of  brownish  sand- 
stone. At  intervals  there  are  lenses  of  fine  grained  soft  sandstone  and 
clay,  about  a  foot  in  thickness  and  all  dipping  40°  to  45""  E.  The 
orientation  of  the  pebbles  in  Jhe  gravel  is  in  the  same  direction,  indi- 
cating an  eastward  tilting  of  the  deposit  as  a  whole  after  its  deposition. 
The  gravel  in  this  tunnel  apparently  carried  little  or  no  gold. 

We  come  now  to  the  pay  gravel,  which  appears  as  a  distinct  layer 
14  to  3  feet  thick,  overlying  the  sandstone  gravel.  This  pay  gravel  is 
composed  entirely  of  igneous,  metamorphic  and  clastic  rocks.  Among 
its  constituents  were  noted:  boulders  of  curly  amphibolitic  schist,  miea- 
garnet  schist,  greenstones,  quartz  in  considerable  quantity  alone,  and 
also  inclosing  broken  fragments  of  the  red  Franciscan  jasper  previously 
mentioned.  This  gravel  is  coarse  and  the  quartz  is  often  angular,  indi- 
cating little  travel.     There  are  occasional  pebbles  of  chromite  and  man- 


46  CALIFORNIA   STATE   MINING  BUREAU. 

ganese  oxides.  Cinnabar  is  found  in  pieces  the  size  of  a  small  bird's 
egg.  Gold  is  occasionally  found  attached  to  rose  quartz.  There  is 
considerable  coarse  black  sand.  A  fresh  contact  could  not  be  observed, 
so  it  can  not  be  said  positively  that  the  pay  gravel  lies  conformably 
on  the  sandstone  gravel,  l)ut  conditions  indicate  that  it  does.  The  gold 
and  platinum,  which  can  be  panned  from  this  i)ay-gravel  stratum  any- 
where along  the  sides  of  the  gulches,  represent  without  doubt  a  reeon- 
eentration.  No  prospecting  has  yet  been  done  in  the  gravel  away  from 
the  gulches.  Good  values  in  gold  and  platinum  metals  can  ])e  panned, 
it  is  claimed,  in  every  gulcli  tr-aversing  the  gravel. 

The  pay  gravel  is  clearly  derived  from  the  Franciscan  metamorphies 
and  from  serpentine  and  later  intrusives  piercing  the  Franciscan.  A 
trip  was  nuule  to  the  east  and  south  for  some  miles,  but  no  gravel 
ecpiivalent  to  it  was  observed,  although  many  terrace  deposits  at  high 
levels  were  seen.  These  are  clearly  stream  deposits,  and  are  often 
identified  at  once  as  stages  of  present  streams.  None  of  them  are  even 
similar  in  character  or  associations  to  the  deposit  under  discussion. 
Prospecting  in  this  direction  has  not  revealed  any  minable  gravel.  The 
l)oundary  of  chert  and  greenstone  to  the  south  and  southwest  appears 
to  be  a  definite  one.  To  the  east  thick  beds  of  brownish  sandstone 
strike  northwest  and  dip  70°  NE.  AVith  this  there  are  numerous  inter- 
bedded  strata  of  dark  clay  shale.  These  are  exposed  in  an  abandoned 
railroad  cut  which  crosses  the  high  ridge  just  east  of  the  road  to  Lake 
county.  On  the  basis  of  hurried  field  observations  only,  this  formation 
is  tentatively  considered  as  lower  Cretaceous.  To  the  west,  across  the 
})resent  Russian  River  valley,  Duncan  Peak  rises  to  a  heiglit  of  about 
1800  feet,  the  dominating  elevation  thereabouts  in  the  coastal  chain.  In 
place  on  its  eastern  slopes  occur  greenstones,  serpentine,  hornblendic 
and  micaceous  schists  representing  Franciscan  metamorphies  and 
intrusives.  Serpentine  is  the  principal  rock  around  the  Duncan  Springs 
resort  buildings  and  narrow  ridges  of  it  extend  eastward  down  the 
slope,  with  some  sandstone  float.  Time  could  not  be  taken  to  trace  the 
sandstone  to  place,  but  it  probably  outcrops  higher  up  as  the  westward 
extension  of  the  Cretaceous  ( ?)  described  above. 

The  local  derivation  of  the  auriferous  gravel  is  emphasized  by  an 
inspection  of  the  gold-bearing  gravel  near  Calpella.  This,  as  men- 
tioned, is  geologically  a  unit  with  the  Hopland  deposit,  although 
erosion  has  removed  the  intervening  link,  which  has  been  traversed  by 
Russian  River.  The  gravel  hills  lie  just  west  of  the  river  south  of 
Calpella.  Gold  Gulch,  emptying  eastward  into  the  river,  cuts  through 
the  gravel  stratum  which  carries  the  gold  and  platinum,  showing  it  to 
rest  on  a  sandstone  gravel  with  occasional  clay  and  shale  lenses, 
identical  with  the   gravel   at  Hopland,   but   dipping  only   20°   NE. 


PLATINUM    AND    ALLIED   METALS.  47 

'he  elevation  of  the  westward  (upper)  edge  of  the  auriferous  irravel 
ras  835  feet  (aneroid),  only  25  feet  below  the  equivalent  point  at 
[opland.  The  black  sand  is  very  fine-frrained  here,  and  there  is  eon- 
derable  fine  quartz  sand.  No  coarse  pieces  of  chroinite,  cinnabar  or 
langanese  oxide  were  seen.  The  gold  and  platinum  grains  are  notiee- 
bly  finer  and  more  water-worn  than  at  Hopland.  All  the  observations 
ossible  in  the  short  time  spent  here  indicate  that  it  is  the  down- 
;ream  extension  of  the  Hopland  deposit.  Further  work  to  the  north 
'ould  be  required  to  prove  that  the  old  stream  once  had  such  a  direc- 
,on,  opposite  to  that  of  the  present  river. 

There  is  no  exposure  of  a  cross-section  in  either  locality  which  shows 
le  presence  of  a  pronounced  stream  channel.  Such  a  channel  may 
ave  existed  on  the  east,  however,  Avhere  the  gravel  is  partly  eroded 
ad  partly  buried  by  the  gravels  of  one  branch  of  jMc^Dowell  Creek, 
'he  thin,  broad  blanket  character  of  the  deposit  indicates  deposition  in 

broad  estuary,  such  as  might  have  existed  there  in  Tertiary  time, 
hen  the  coast-line  was  approximately  in  that  neighborhood. 

The  manner  in  which  this  gravel  has  been  saved  from  destruction  by 
rosion,  is  of  interest.  This  may  have  been  brought  about  by  folding 
p  by  the  faulting  down  of  a  block,  which  has  been  preserved,  while  the 
mtheastward  portion  has  been  eroded  away.  Or  it  may  be  that  the 
ravel  in  a  syncline  has  been  partly  mantled  and  preserved  by  Quater- 
ary  alluvium.  The  final  tilting  came  after  the  deposition  of  the  gold- 
latinum  bearing  gravel,  giving  the  eastward  dip,  and  differentiating 
le  deposit  from  Quaternarj^  stream  terrace  gravels  which  can  be  seen 
Qly  a  few  miles  east. 

Recent  hand  mining  with  pan  and  rocker  in  two  of  the  gulches 
raining  the  deposit  gave  surprising  returns,  attributable  to  the  con- 
mtration  of  values  in  the  little  stream  beds.  Over  two  ounces  of 
latinum  metals  were  taken  out  in  this  way.  One  test  gave  190  grains 
I  gold  and  160  grains  of  platinum.  The  platinum  metal  shows  the 
nigh  crystalline  character  of  osmiridium,  little  affected  by  wear.  An 
5say  by  A.  A.  Hanks  indicates  49%  iridium.  32%  osmium  and  10% 
)ft  platinum.  Unfortunately,  the  deposit  at  Hopland  is  so  situated 
lat  there  is  no  water  supply  of  sufficient  size  readily  available  for 
lining  it.  The  only  streams  nearby  are  too  small  to  be  of  service 
Kcept  during  storms.  A  branch  of  Burns  Creek  has  been  restrained 
y  a  dam  near  the  southeast  end  of  the  deposit,  ])ut  the  flow  here, 
hich  would  have  to  be  pumped,  is  too  small  and  torrential  in  character 
)  be  of  any  use.  Russian  River  is  375  feet  below  the  deposit  at  the 
earest  point.  The  property  would  have  to  he  thoroughly  prospected 
1  order  to  show  whether  or  not  the  iustalhition  of  a  pipe  line  several 


48  CALIFORNIA    STATE    MINING   BUREAU. 

miles  long  would  be  justified.    The  present  showing  is  such  that  extensivj 
exploratory  work  by  means  of  shafts  and  trenches  is  fully  warranted. 

If   such    prospecting    confirms    as    wide    distribution    of    gold    anc 
platinum  as  the  richness  of  the  wash  in  the  various  gullies  indicate 
the  pay  gravel  could  be  stripped  of  soil  and  mined  at  slight  expense 
In  the  absence  of  adecpiate  water  supply,  a  preliminary  concentratioi 
by  dry  washing  ought  to  be  practicable.     Enough  water  for  final  conj 
centration  could  probably  be  developed  by  sinking  wells  into  the  gravej 
on  the  east  side  and  pumping. 

TEHAMA-SHASTA  COUNTIES. 
Beegum  Creek. 

A  small  area  along  Beegum  Creek,  from  the  crossing  of  the  Stat 
Highway  to  the  beginning  of  the  box  caiion,  a  distance  of  about  om 
mile  in  all,  attracted  some  attention  in  1917-1918  when  several  ounc 
of  platinum  were  taken  out.  The  writer  spent  two  days  in  the  distric 
with  the  idea  of  finding  out  definitely  the  manner  of  occurrence  of  tb 
platinum  and  the  size  of  the  area  which  could  be  worked  profitably. 

The  creek  here  forms  the  county  line  between  Tehama  and  Shast 
counties.  The  slopes  are  gentle,  there  being  a  gradual  ascent  fro 
Beegum  Creek  at  the  Selvester  Ranch  to  the  divide  between  the  Sacr 
mento  and  Trinity  watersheds,  a  distance  of  thirteen  miles.  Beegu 
Creek  has  formed  a  gravel  flat  here  which  has  been  mined  someAvhat 
the  past  for  gold,  but  is  now  under  cultivation.  The  stream  is  sluggis 
in  this  graded  portion,  but  less  than  a  mile  below  it  enters  a  narro 
canon  and  gains  grade.  Its  upper  branches  drain  the  serpentine  are 
around  Tcdoc  Mountain  to  the  south,  and  its  northern  fork  reachei 
into  the  Trinity  Mountains,  but  carries  an  insignificant  amount  o 
water  in  summer.  Beegum  Peak,  the  prominent  natural  feature  of  th 
neighborhood,  is  so  named  because  of  its  profile,  resembling  the  rounde 
outline  of  a  bee-hive.  It  is  covered  by  conglomerate,  which  appears  t 
be  made  entirely  of  chert  pebbles  from  the  size  of  shot  to  1|  inch  i 
diameter.  This  chert  is  the  rock  encountered  for  a  distance  of  eight] 
miles  on  the  road  to  the  Tedoc  chromite  deposits,  giving  place  to  the 
conglomerate  one-fourth  mile  from  Beegum  Peak.  On  the  Selveste 
Ranch  near  the  highway,  the  creek  enters  a  bed  of  alternating  thii 
laminations  of  dark  shale  and  sandstone.  These  strike  about  N.  10°  E 
and  dip  45°  E.  and  the  stream  has  cut  a  wide  V-shaped  trench  througi 
them.  The  stream  bed  in  a  distance  of  one-fourth  mile  begins  to  picl 
up  grade,  and  becomes  narrower,  flowing  over  slate  which  dips  at  a  lovi 
angle  and  is  broken  up  into  thin  sheets.  In  the  miniature  caiion  th( 
stream  has  formed  a  flood  deposit  of  sand  and  gravel  1  to  2  feet  thick 
but  in  the  summer  the  water  is  only  12  to  15  feet  wide  and  runs  nea: 
the  south  bank. 


* 


PLATINUM    AND   ALLIED    METALS.  49 

Panning  in  the  gravel  of  Beegum  Creek  on  the  upper  part  of  tiie 
Selvester  Ranch  shows  only  an  occasional  color  of  platinum.  The  creek 
bed  is  for  the  most  part  choked  with  detrital  material  and  the  grade 
is  so  low  that  mining  would  be  difticult  in  it.  There  is  probably  a 
certain  amount  of  platinum  in  the  stream  here,  but  it  is  so  situated 
under  a  mantle  of  barren  sand  that  it  is  doubtful  if  mining  it  would 
be  profitable.  This  is  the  case  because  of  the  small  scale  methods  that 
would  be  used.  At  the  lower  end  of  this  property  the  stream  takes  on 
grade  enough  to  clear  its  bed  of  sand.  Panning  here  of  the  material 
taken  from  the  crevices  in  the  slaty  creek  bed  at  the  summer  water 
level  gave  a  surprising  prospect  of  platinum.  The  following  shows  the 
results  with  a  |  size  pan : 

(1)  13  colors  platinum;     3  colois  gold. 

(2)  4  colors  platinum;     5  colors  gold. 

(3)  15  colors  platinum;     3  colors  gold. 

(4)  6  colors  platinum;     4  colors  gold. 

(5)  8  colors  platinum;  no  colors  gold. 

The  platinum  colors  ranged  in  size  from  a  pinhead  down  to  'flour.' 
In  striking  contrast,  several  pans  taken  from  the  flood-stage  gravels 
which  lie  to  one  side  of  the  summer  channel  and  mantle  the  slate  bed- 
rock, failed  to  jdeld  any  colors  of  platinum.  About  one-fourth  of  a  mile 
below  this,  panning  the  material  from  the  fiat  crevices  in  slate  at  the 
water's  edge  gave  the  following: 

(1)  20  colors  platinum;   1^-3  colors  gold. 

(2)  8  colors  platinum;       4  colors  gold. 

(3)  11  colors  platinum;       2  colors  gold. 

(4)  55-60  colors  platinum;       4  colors  gold. 

Panning  the  gravel  on  the  bedrock  10  feet  back  from  the  water's  edge 
failed  to  show  any  platinum  or  gold. 

Downstream  200  yards  from  this  point  the  stream  enters  the  chert, 
which  has  occasional  limestone  lenses  witli  it.  No  colors  of  platinum 
were  found  here  and  it  is  not  thought  that  mining  where  the  creek 
cro.sses  this  rock  would  yield  a  profit.  The  chert  does  not  offer  a  riffle 
for  the  platinum,  but  on  the  contrary  would  tend  to  scour  out  clean 
during  high  water.  There  is  an, exposure  of  gravel  lying  on  indiiiMtcd 
clay  shale  adjacent  to  the  creek  near  the  chert  contact.  One  or  two 
minute  grains  of  platinum  can  l)e  obtained  in  nearly  every  pan  from 
the  lower  two  feet  of  this  gravel.  The  waiter  came  to  the  conchision 
that  the  area  which  could  be  mined  with  a  profit  here  was  coniined 
to  the  slate  bedrock  of  the  creek  for  a  di.stance  of  about  one-half  mile 
and  a  width  of  about  12'  to  15'.  There  appeared  to  be  no  values  in 
the  gravel  or  on  the  bedrock  away  from  the  edge  of  the  stream.  This 
gravel  had  been  mined  off  to  bedrock  and  the  latter  carefully  cleaned 
from  the  water's  edge  to  the  wall  of  the  miniature  canon.  In  order  to 
determine  whether  my  conclusions  regarding  the  deposit  were  correct 

4—46903 


50  CALIFORNIA   STATE   MINING   BUREAU. 

I  sought  out  the  owuer  at  a  later  date.  It  developed  that  the  area 
100  feet  long  and  20  feet  wide,  back  from  the  stream,  had  yielded  prac- 
tically nothing,  but  that  about  5  ounces  of  platinum  with  a  little  gold, 
had  been  recovered  from  a  very  small  area  of  the  stream  bed  where  the 
slate  had  been  dug  up  and  the  crevice  filling  washed  in  sluices.  This 
was  in  addition  to  unkno^^^l  small  quantities  mined  surreptitiously  l)y 
people  who  had  no  right  on  the  ground. 

The  platinum  here  appears  to  be  the  result  of  concentration  from 
the  adjacent  gravels  through  which  the  stream  has  cut.  In  the  gravels 
themselves  the  concentration  of  platinum  is  apparently  not  sufficient  to 
pay.  The  slaty  bedrock  has  oft'ered  an  exceptionally  good  riffle  for 
detaining  the  metal  and  the  creek  has  been  a  natural  sluice  in  times  of 
high  water.  Time  could  not  be  taken  to  trace  the  platinum  down  tln' 
stream,  but  parties  Avho  had  mined  at  the  mouth  of  Beegum  Creek 
reported  gold  and  platinum  in  very  small  quantity,  not  enough  to  pay 
wages  for  hand  mining.  The  boundary  of  the  gravel  is  half  a  mile 
above  the  highway  bridge,  and  as  far  as  reported,  no  platinum  had  bem 
found  above  this  gravel.  An  assay  of  platinum  from  Beegum  Creek 
was  made  some  years  ago  by  Shapeleigh.  It  is  sliown  in  the  appended 
table. 

Since  the  district  was  visited,  other  claims  have  been  staked  near 
the  stream  above  the  Selvester  property,  and  the  district  is  being  i)ros- 
pected  to  determine  whether  or  not  development  work  will  be  justified 


YOLO  COUNTY. 

Platinum  occurs  in  gravel  near  the  mouth  of  Putah  Creek,  just  wesi 
of  Winters  in  Yolo  County.  George  T.  Ruddock^  reports  that  when 
prospecting  here  some  years  ago,  he  obtained  from  2  to  11  coarse  colors 
of  platinum  with  a  subordinate  amount  of  gold  in  practically  every  pan 

The  gravel  prospected  was  taken  from  the  little  gullies  w^hich  carry 
off  rain  water  during  the  winter  season,  but  are  dry  most  of  the  year 
Probably  there  has  been  considerable  concentration  of  platinum  here 
the  gravel  on  the  hillsides  away  from  the  gullies  has  not  been  prospected 

The  deposit  is  described  by  Ruddock  as  a  conglomerate  dipping  north- 
east and  containing  cobbles  of  quartz,  granite  and  diorite.  He  citei 
the  presence  of  granite  as  evidence  that  the  gravel  came  from  the 
Sierra  Nevada  side.  Nevertheless,  it  is  possible  that  close  investigation 
would  result  in  connecting  this  conglomerate  with  other  areas  oi 
Cretaceous  conglomerate  which  are  so  prominent  to  the  north  on  the 
west  side  of  the  Sacramento  Valley,  or  with  the  Tertiary  gravels  oi 
shore    origin   which   overlap    the    Cretaceous   beds.     The    presence   o: 


^Mining  Engineer,  Insurance  Exchange  Bldg.,  San  Francisco.     Personal  interview. 


PLATINUM   AND    ALLIED    METALS.  51 

granitic  cobbles  in  the  conjilonieratc  is  in  no  way  conclusive,  as  granitic 
wash  can  be  found  in  several  (Icjjosits  in  the  northwestern  counties 
which  contain  platinum,  and  granite  bosses  of  varying  size  underlie  a 
large  part  of  the  Klamath  IMountains. 

The  conglomerate  near  Winters  has  an  area  of  several  scpiare  miles, 
sloping  up  on  the  west  in  a  gentle  fold.  It  is  tliought  that  it  would  be 
possible  to  work  only  the  weathered  surface  portion,  as  in  depth  it 
becomes  cemented.  The  total  thickness  has  not  been  determined,  but 
is  known  to  be  great.  Plans  for  dredging  it  were  once  entertained. 
Water  could  be  pumped  from  Putah  Creek;  a  lift  of  150  feet  to  a 
reservoir  would  put  the  supply  high  enough  to  be  used  in  sluicing  the 
dirt  down  the  gullies,  and  would  also  give  sufficient  supply  to  fili  a 
dredge  pond  lower  down.  Inability  to  reach  an  agreement  with  the 
owners  led  to  abandoning  the  project. 


52  CALIFORNIA    STATE   MINING   BUREAU. 


HYDRAULIC  MINING. 

Hydraulic   mining  practice  today  varies  little   from  that  followed! 
twenty-five  years  ago.     The  long  fight  of  the  Sacramento  valley  farmers,! 
which  resulted  in  the  disruption  of  this  branch  of  mining  in  the  Sierraj 
Nevadas,    left    only    the    northwestern    California    counties    open    to 
hydraulicking.     The  man  with  a  giant  and  long  string  of  sluices  has! 
been  content  to  save  such  gold  as  lodged  between  blocks  and  riffles  and! 
has  paid  little  or  no  attention  to  values  lost  with  the  tailing.     He 
recognizes  that  his  method  is  at  best  very  crude.     Its  advantages  are 
its  cheapness  of  installation  and  operation,  and  the  large  yardage  that  it 
handles.     Even  such  refinement  as  an  undercurrent  is  frowned  on  by 
most  operators  because  they  claim  it  takes  too  much  water  from  the_ 
sluice. 

The  La  Grange  mine  in  Trinity  County  has  worked  on  a  larger  scale] 
than  any  other  property  and  at  the  same  time  has  paid  more  attention, 
to  saving  than  most,  as  the  gravel  there  has  been  of  low  grade.     This 
company's  operations  are  well  described  by  MacDonald.^     The  great 
success  in  saving  fine  gold  there  is  ascribed  to  the  eddying  action  in  the; 
sluice  which  is  caused  by  the  shape  of  the  steel  rails  which  are  used 
for  riffles.     The  grade  of  the  sluice  is  seven  inches  to  twelve  feet  in  thej 
upper  portion,  and  eight  inches  in  the  lower  portion,  and  the  boxes  are! 
four  by  six  feet,  the  insides  being  lined  with  the  bases  of  the  rails! 
which  have  had  the  tops  worn  away  in  the  sluice  while  being  used  aaj 
riffles.     The  curve  of  settlement  for  gold  of  different  sizes  has  beenj 
investigated  at  this  mine.     The  coarsest  pieces,  larger  than  10  mesh, 
which  form  over  one-half  the  total  gold,  stop  principally  in  boxes  11,  5,J 
12  and  13,  the  first  named  receiving  more  than  the  others  and  thej 
amount  decreasing  rapidly  from  box  13  onward.     From  10  to  50-mesh] 
gold  stops  largely  on  the  w^ay  to  box  12  and  that  box  marks  the  maxi- 
mum recovery  of  these  sizes.     The  bulk  of  gold  finer  than  50  mesh  I 
stops  in  the  first  13  boxes;  box  22  is  another  period  in  the  recovery, 
as  the  gold  of  all  sizes  which  passes  it  does  not  seem  to  settle  so  rapidly] 
beyond  it,  but  spreads  out  over  the  remaining  boxes. 

Few  of  the  hydraulic  mines  of  northwestern  California  are  adequately] 
equipped  with  water.     The  La  Grange  in  Trinity  County,  the  Forks 
of  Salmon  River  mine  on  the  Salmon,  and  the  Davis  and  Siskiyou  mines 
at  Happy  Camp  are  the  only  properties  able  to  operate  continuously. 
The  La  Grange  has  29  miles  of  ditch,  flume  and  tunnel  and  gets  20001 
miner's  inches,  but  even  with  this  splendid  supply  they  ran  short  inj 
the  fall  of  a  dry  season  like  1917.     The  Forks  of  Salmon  River  mine 


^U.  S.  G.  S.  Bull.  430,  p.  51.     (This  property  is  now  idle.) 


PLATINUM    AND   ALLIED    METALS. 


53 


diverts  practically  the  entire  suninier  tiow  of  the  Nortli  Fork  of  Salmon 
into  their  mining  ditch,  whicli  is  five  miles  long,  and  furnisliwi  enough 
water  for  steady  operation.  But  the  balance  of  the  hydraulic  properties 
operate  over  a  period  not  exceeding  six  months  and  in  many  cases  only 
three   months    of    the   actual    storm    period,    January    to    Ai)ril.     The 


Photo  No.  3.     Bedrock  cut  and  sluice,  Orleans  Bar  Hydraulic 
Mine,     Humboldt    County. 

expense  of  digging  and  maintaining  a  long  ditch  is,  of  course,  too  heavy 
for  the  average  small  property  to  stand.  Their  production  does  not 
warrant  it.  The  area  of  ground  worked  yearly  at  the  smaller  hydraulic 
mines  is  seldom  over  an  acre  and  the  annual  clean-up  is  from  $1,000 
to  $5,000.  There  are  several  properties  big  enough  to  justify  the 
installation  of  a  water  system  comparable  to  the  La  Grange  equipment, 
but  no  one  with  the  capital  and  the  breadth  of  vision  needed,  has  yet 
taken  hold  of  them. 


54  CALIFORNIA    STATE    MINING   BUREAU. 

Bedrock  sluices  vary  witli  the  size  of  the  property.  Some  gravel 
deposits  are  .situated  so  that  they  give  good  natural  run  off  and  the 
sluice  boxes  can  be  carried  nearly  up  to  the  gravel  face.  Others  with 
broad,  nearly  level  benches  like  the  mines  near  Junction  City  require 
long  bedrock  cuts  60  feet  or  more  deep.  The  putting  down  of  such  a 
cut  is  an  expensive  and  slow  job  and  requires  rich  gravel  to  justify  it. 
Strings  of  sluices  in  most  mines  are  probably  rather  short  to  give 
best  results.  The  La  Grange  mine  carries  3000  feet  of  sluices  with  a 
fork  in  the  lower  portion  to  permit  the  diversion  of  the  gravel  and  the 
cleaning  of  the  lower  boxes  on  one  side  of  the  fork.  Avithout  stopping 
mining.  A  few  properties  have  as  much  as  one-fourth  of  a  mile  of  sluices 
but  the  majority  have  not  over  500  feet.  Pine  blocks  are  used  almost 
entirely  for  riffles.  Some  of  the  mines  are  equipped  with  saw-mills 
but  for  the  most  part  they  are  hand  sawed.  Sprinkling  a  little  quick- 
silver among  the  blocks  completes  the  preparation  for  mining. 

Tlie  ordinary  practice  requires  bedrock  sloping  down  to  the  sluiceway. 
There  are  a  few  properties  where  the  grovind  has  to  be  attacked  from 
the  opposite  direction  and  it  then  becomes  necessary  to  pipe  up  to  the 
boxes.  This  requires  hard  work  and  a  big  head  of  water,  with  an  extra 
giant.     A  property  of  this  kind  is  being  operated  near  Weaverville. 

The  Ru])le  elevator  has  been  successfully  used  to  mine  ground  which 
is  too  nearly  level  to  offer  grade  for  sluices  and  dump.  These  elevators 
are  used  entirely  by  the  iMichigan-Salmon  ^Mining  Company,  on  the 
South  Fork  of  Salmon  River.  The  elevator  is  90  feet  long  and  8|  feet 
wide  and  with  sides  6  feet  high.  It  is  essentially  a  long  sluice  box,  set 
at  an  inclination  of  17°  and  the  gravel  is  driven  through  the  box 
against  this  grade  in  order  to  elevate  it.  The  bottom  of  the  box  for 
62  feet  is  a  grizzley  fitted  with  cross  riffles  of  2  by  4  timber,  iron-faced 
and  set  2  inches  apart.  Under  the  grizzley  and  at  right  angles  to  the 
length  of  the  elevator  there  is  a  wide  sluice  50  feet  long  which  receives 
the  material  under  two  inches  coming  through  the  grizzley.  This  is  the 
onl}^  sluice  used  and  is  said  to  make  an  excellent  recovery.  This  good 
work  is  probably  due  to  the  removal  of  the  coarse  material,  and  to  the 
wide  sluice  with  plenty  of  water.  The  ground  mined  is  especially 
adapted  to  this  method  of  operation  as  there  is  no  soil  overburden  and 
no  very  large  boulders.  In  mining,  three  No.  3  giants  with  457  feet 
head  are  used.  One  giant  is  used  exclusively  for  driving  the  gravel 
through  the  elevator.  The  coarse,  gravel  which  will  not  pass  through 
the  grizzley  is  driven  over  the  upper  end  of  the  elevator  and  piles  up 
in  stacks  resembling  dredger  tailings.  Extra  stacking  height  can  be 
gained  by  increasing  the  length  of  the  elevator.  The  elevators  cost 
about  $5000  each  to  install,  have  a  long  life,  and  are  moved  around  the 
diggings   without   much    trouble.     They   require    a   large    amount   of 


.;- 


TJlt 


%ouK 


1^7^ 


mf"^^--.- 


PLATINUM   AND   ALLIED   METALS.  55 

water  under  heavy  pressure  and  handle  from  1000  to  2000  cubic  yards 
af  gravel  in  24  hours. 

Prospecting  of  hydraulic  mining  ground  may  begin  by  tracing  the 
trail  of  gold  colors  up  a  canon  side.  This  method  sometimes  discloses 
the  presence  of  good  terrace  gravels  which  may  be  entirely  mantled  by 
slide  debris.*  To  determine  the  availability  of  a  deposit  for  hydraulic 
mining,  the  situation  of  ground  as  regards  grade  for  slnices  and  room 
for  dump  must  be  determined.  It  nnist  be  under  water  which  can  be 
delivered  in  sufticient  quantity  at  high  enough  pressure.  Tlie  amount 
of  overburden  barren  of  values,  must  be  known,  so  that  the  yardage  of 
dead  wash,  which  must  be  moved  to  get  at  pay  gravel,  can  be  figured. 
The  physiography  of  the  country  must  be  considered.  The  grade  of  a 
canon  superjacent  to  a  gravel  deposit  may  equal  the  angle  of  repose, 
or  the  material  may  be  especially  susceptible  to  sliding,  like  serpentine, 
so  that  the  gravel  is  kept  covered  by  debris  as  fast  as  it  is  cut  by  the 
water.  This  latter  condition  is  also  of  prime  importance  in  establishing 
a  water  system.  There  are  numerous  small  bodies  of  gravel  on  the 
Klamath  River  which  can  not  be  hydraulicked  advantageously  on 
account  of  interfering  slides.  Flumes  and  ditches  across  tiiis  sliding 
ground  give  a  great  deal  of  trouble  and  there  is  annually  great  loss 
and  delay  due  to  interruption  of  water  supply  in  stormy  weather.  Such 
delays  are  at  times  unavoidable,  and  nuist  be  figured  in  the  cost  of  the 
season's  run.  If  there  is  a  heavy  cement,  it  may  prevent  piping,  and 
if  boulders  are  so  large  as  to  require  much  blasting  or  a  derrick,  cost 
is  appreciably  increased.  Gravel  mantled  by  too  heavy  overburden,  or 
by  volcanic  material  too  hard  to  pipe,  is  not  hj^draulic  ground.  Such 
ground  becomes  susceptible  to  drifting  if  the  gravel  on  and  within  six 
feet  of  the  bedrock  is  rich  enough.  All  these  conditions  are  easily 
appreciated,  and  most  of  them  are  determinable  during  preliminary 
investigation;  yet  it  is  true  that  they  are  constantly  ignored  in  the 
exploitation  of  hydraulic  mining  properties. 

The  actual  sampling  of  gravel  has  often  been  done  by  running 
prospect  drifts  into  the  deposit.  These  can  be  made  to  show  the 
breadth  of  the  deposit,  the  location  of  pay  streaks,  and  amount  of  gold 
a  yard,  the  nature  of  bedrock,  grade  of  channel  and  other  features 
liable  to  affect  mining. 

DEL  NORTE  COUNTY. 
Topography   and    Relief. 

The  boundaries  of  Del  Norte  County  are  nearly  coincident  with  those 
of  the  Smith  River  basin.  The  coastal  plain  has  a  width  of  about  five 
miles  near  the  river's  mouth  and  extends  south  to  four  miles  beyond 


*One  of  the  best-paying,  small  bodies  of  terrace  gravel  opened  In  recent  years  on 
Salmon  River  was  uncovered  in  this  way.     It  was  concealed  by  sl-.l..-^  .....i  i...d  i.^-.  n 


ver 
overlooked  for  50  years 


Jt' 


1  jun  'rva  "5  O  ' 


t* 


PLATINUM   AND   ALLIED   METALS.  55 

^vater  under  heavy  pressure  and  handle  from  1000  to  2000  cubic  yards 
3f  gravel  in  24  hours. 

Prospecting  of  hydraulic  mining  ground  iiia\    begin  by  tracing  the 
trail  of  gold  colors  up  a  canon  side.     This  method  sometimes  discloses 
the  presence  of  good  terrace  gravels  which  may  be  entirely  mantled  by 
slide  debris.*     To  determine  the  availability  of  a  deposit  for  hydraulic 
mining,  the  situation  of  ground  as  regards  grade  for  sluices  and  room 
for  dump  must  be  determined.     It  must  be  under  water  which  can  be 
delivered  in  sufficient  quantity  at  high  enough  pressure.     The  amount 
of  overburden  barren  of  values,  must  be  known,  so  that  the  yardage  of 
dead  wash,  which  must  be  moved  to  get  at  pay  gravel,  can  be  figured. 
The  physiography  of  the  country  nuist  be  considered.     The  grade  of  a 
canon  superjacent  to  a  gravel  deposit  may  equal  the  angle  of  repose, 
or  the  material  may  be  especially  susceptible  to  sliding,  like  serpentine, 
so  that  the  gravel  is  kept  covered  by  debris  as  fast  as  it  is  cut  by  the 
water.     This  latter  condition  is  also  of  prime  importance  in  astablishing 
a  water  system.     There  are  numerous  small  bodies  of  gravel  on  the 
Klamath   River   which    can   not   be   hydraulicked   advantageously   on 
account  of  interfering  slides.     Flumes  and  ditches  across  this  sliding 
ground  give  a  great  deal  of  trouble  and  there  is  annually  great  loss 
and  delay  due  to  interruption  of  water  supply  in  stormy  weather.    Such 
delays  are  at  times  unavoidable,  and  must  be  figured  in  the  cost  of  the 
season's  run.     If  there  is  a  heavy  cement,  it  may  prevent  piping,  and 
if  boulders  are  so  large  as  to  require  much  blasting  or  a  derrick,  cost 
is  appreciably  increased.     Gravel  mantled  by  too  heavy  overburden,  or 
by  volcanic  material  too  hard  to  pipe,  is  not  hydraulic  ground.     Such 
ground  becomes  susceptible  to  drifting  if  the  gravel  on  and  within  six 
feet  of  the  bedrock  is  rich  enough.     All  these  conditions  are  easily 
appreciated,  and  most  of  them  are  determinable  during  preliminary 
investigation;  yet  it  is  true  that  they  are  constantly  ignored  in  the 
exploitation  of  hydraulic  mining  properties. 

The  actual  sampling  of  gravel  has  often  been  done  by  running 
prospect  drifts  into  the  deposit.  These  can  be  made  to  show  the 
breadth  of  the  deposit,  the  location  of  pay  streaks,  and  amount  of  gold 
a  yard,  the  nature  of  bedrock,  grade  of  channel  and  otlicr  features 
liable  to  atfect  mining. 

DEL  NORTE  COUNTY. 
Topography   and    Relief. 

The  boundaries  of  Del  Norte  County  are  nearly  coincident  with  those 
of  the  Smith  River  basin.  The  coastal  plain  has  a  width  of  about  five 
miles  near  the  river's  mouth  and  extends  south  to  four  miles  beyond 

*One  of  the  best-paying,  small  bodies  of  terrace  gravel  opened  in  rec-ent  yem 
Salmon  River  was  uncovered  in  this  way.     It  was  concealed  by   slid.  ^    .n.i   h.ui 
overlooked  for  50  years. 


56  CALIFORNIA   STATE   MINING   BUREAU. 


Crescent  City,  where  it  gives  way  to  the  Sherwood  peneplain.^  This 
plateau  fronts  steeply  on  the  ocean,  but  descends  more  gradually  to  the 
Klamath,  which  enters  the  ocean  about  five  miles  north  of  the  Humboldt 
County  line.  This  river  is  wide  and  sluggish  in  its  lower  course, 
meandering  over  a  low  plain  for  some  distance.  I 

Going  eastward  from  Crescent  City  toward  the  South  Fork  of  Smith 
River,  one  crosses  the  beautiful  Redwood  belt,  covering  the  lower  hills. 
These  trees  require  much  moisture  and  good  soil,  and  they  disappear 
at  the  divide  which  cuts  off  the  ocean  fogs  and  marks  the  beginning 
of  the  rockier  mountain  spurs.  The  old  peneplain  surface  is  preserve 
in  many  flat  topped  mountains  along  the  whole  length  of  the  county, 
High  Plateau  at  the  nortli  has  a  maximnm  elevation  of  3500  feet  and' 
has  a  cliff-like,  unpassable  front  on  Smith  River's  northern  fork,  2500 
feet  below.  French  Hill,  ])etween  the  South  and  Middle  forks  near 
their  junction,  has  for  several  miles  a  nearly  level  surface  near  the  2000 
foot  contour.  This  flat  exhibits  a  gentle  slope  to  the  south  and  west. 
Similarly,  Lower  Coon  Mountain  and  Big  and  Little  Rattlesnake 
mountains  show  long,  flattish  tops,  from  about  3000  to  3500  feet  in 
elevation. 

The  forks  of  Smith  River  and  their  tributaries  have  deeply  dissected 
this  peneplain.  Canon  sides  are  sometimes  very  steep,  and  the  streams 
flow  in  narrow  rocky  trenches.  The  cafion  of  the  Middle  Fork,  viewed 
from  the  road  from  Adams  Station  to  the  Oregon  line,  is  especially 
picturesque,  showing  the  river  as  a  bright  ribbon,  2500  feet  below  some 
of  the  mountains  to  the  south,  which  are  remnants  of  the  old  surface. 
The  main  axis  of  the  Siskiyou  IMountains  runs  nearly  north  and  forms 
the  ea.stern  boundary  of  the  river  basin  and  the  county.  The  upper 
waters  of  one  branch  of  Illinois  River  drain  the  extreme  northeastern 
corner  of  the  county.  Many  peaks  over  6000  feet  in  height  stand  along 
the  county  line,  and  the  country  is  rough  and  practically  uninhabited. 


Drainage  and  Water  Resources. 

Smith  River  drains  most  of  Del  Norte  CoiTuty  and  some  of  its 
northern  tributaries  extend  into  Oregon.  Its  basin  is  separated  from 
that  of  the  Klamath  by  the  Siskiyou  Mountains  which  are  from  4000  to 
7500  feet  high,  on  the  east  and  south.  The  Illinois  River  watershed  lies 
to  the  northeast,  beyond  mountains  which  reach  a  maximum  height  of 
5000  feet.  The  portion  of  the  Smith  River  basin  lying  in  California  is 
very  nearly  700  square  miles  in  area. 

The  North  Fork  rises  near  South  Red  Mountain  in  southern  Oregon 
and  flows  south  past  the  steep  scarp  of  High  Plateau,  entering  the 
Middle  Fork  opposite  Gasquet  Stage  Station  at  an  elevation  of  only 


I 


'Diller,    J.    S. :    U.    S.    Geol.    Surv.    Bull.    196.     Topographic    Development    of    the 
Klamath  Mountains. 


PLATINUM    AND   ALLIED    METALS.  57 

376  feet.  The  ]Middle  Fork,  with  its  main  l)ranc'h,  tlie  Siskiyou  Fork, 
drains  the  mountainous  area  from  Sanger  Peak  to  Doe  Flat  Saddle. 
It  flows  most  of  the  way  in  a  steep  cailon,  with  only  an  occasional 
narrow  bench  of  flat  ground,  till  it  approaches  its  junction  with  the 
North  Fork,  where  it  flows  through  a  pleasant  valley  about  one-half 
mile  wide  and  five  miles  long.  The  South  Fork  heads  against  Doe  Flat 
Saddle,  with  its  source  close  to  the  upper  waters  of  Siskiyou  Fork.  It 
flows  south  for  twelve  miles,  then  west  and  northwest  for  twenty-five 
miles,  entering  the  other  branch  at  Christensen 's  Ranch,  elevation  260 
feet.  This  fork  is  a  beautiful  stream  of  crystal  clearness  flowing  for 
considerable  distances  in  a  box  canon  witli  only  occasional  deposits  of 
bench  gravel.  From  the  junction  at  South  Fork,  the  river  flows  north- 
west through  a  redwood  forest  and  enters  the  ocean  in  an  estuary  about 
four  miles  .south  of  the  Oregon  line. 

This  stream  maintains  a  good  flow  in  summer,  having  many  tribu- 
taries which  reach  into  the  high  mountains.  Grades  are  steep.  There 
is  ample  water  available  for  Avorking  the  gravels  which  lie  near  the 
river,  but  there  are  a  few  of  the  older  and  higher  deposits  which  would 
require  ditches  five  to  ten  miles  long  to  get  an  adequate  supply.  There 
are  no  deposits  of  gravel  in  Del  Norte  County  which  compare  in  size 
Avith  the  bench  gravels  of  the  counties  to  the  south,  and  the  question  of 
water  supply  is  never  going  to  be  a  pressing  one.  Mining  operations 
are  likely  to  be  only  on  a  limited  scale.  Very  little  of  the  available 
water  supply  has  yet  been  appropriated.  Rainfall  is  heavy,  being 
about  100  inches  per  annum  along  the  coast  belt,  and  summer  is  cool, 
so  that  the  streams  give  a  perennial  supply  capable  of  serving  any 
mining  needs  apt  to  arise. 

Geology. 

The  coastal  plain  from  Smith  River  southward  past  Crescent  City 
shows  few  outcrops  of  rock  in  place.  Diller  ascribes  tlie  low  plain  to 
the  softness  of  the  Neocene  formations.  Farther  inland,  a  belt  of 
Franciscan  rocks  traverses  the  county.  This  Is  bounded  by  the  Red- 
wood IMountain  fault  and  is  succeeded  by  a  zone  of  eruptive  rocks 
which  increases  in  width  toward  the  north,  covering  an  area  of  over 
two  townships  where  it  crosses  the  state  line  into  Oi-cgon.  This  belt  is 
made  up  of  serpentine  and  peridotite  chiefly,  but  there  are  many 
tongues  of  gray-green  'diorite'  intruded  in  it.  Tlie  peridotite  is 
prominent  in  the  northern .  part  of  the  county.  The  road  from 
Smith  River  to  Patrick  Creek  traverses  a  wide  stretch  of  it 
which  extends  north.  It  forms  rocky,  forbidding  slopes,  weathering 
to  a  soil  Avhich  supports  only  scrubby  brush.  Here  it  is  not  entirely 
serpentinized.  but  serpentine  is  prominent  along  the  river,  forming 
bedrock  in  the  h}draulic  mines  on  botli  forks  and  to  the  east  of  the 


58  CALIFORNIA   STATE   MINING  BUREAU. 

South  Fork,  as  well  as  on  French  Hill.  This  serpentine  belt  is  of 
great  importance  because  the  principal  deposits  of  chromite,  gold, 
copper  and  platinum  are  situated  near  its  edges,  owing  their  genesis 
probably  to  magmatic  segregation  from  the  serpentine  or  diorite.  The 
chromite  deposits  at  Low  Divide  and  French  Hill,  which  have  been 
producing  large  tonnages  of  high  grade  ore  during  the  past  year,  are 
botb  located  near  such  contacts.  The  best  copper  prospects  are  also 
located  near  similar  contacts.  The  same  action  is  considered  by  the 
writer  to  be  responsible  for  deposition  of  gold,  found  typically  in 
Mj'rtle  Creek.  Besides  the  chromite  properties  mentioned,  recent 
prospecting  has  revealed  promising  deposits  on  High  Plateau  just  east 
of  the  North  Fork,  and  to  the  east  and  south  of  French  Hill  for  a 
clistance  of  fifteen  miles. 

South  and  west  of  the  serpentine  is  an  area  of  metamorphics  named 
Weitehpec  schists  by  some  previous  observers,  because  of  their  occur- 
rence near  Weitehpec  viUage  on  tlie  Klamath  River  in  Humboldt 
County.  The  geology  of  the  country  thence  eastward  to  the  county 
line  has  never  been  studied  except  casually.  0.  H,  Hershey  indicates 
the  extension  northward  of  igneous  rocks  of  undetermined  age,  in  a 
l)elt  from  the  Klamath.  A  belt  of  slates,  presumably  equivalent  to  the 
jMariposa,  according  to  Hershey,  extends  from  the  Klamath  River 
nortliward  far  into  Del  Xorte  County  east  of  the  serpentine  zone,  and 
is  bounded  on  the  east  by  the  Orleans  fault.  Hershey  also  indicates 
that  a  narrow  belt  of  old  schists  borders  the  fault  on  the  east.  Vol- 
canics  forming  the  higher  Siskiyous  near  the  county  line  are  succeeded 
by  a  second  serpentine-' diorite'  zone,  having  the  same  characteristics 
as  the  west  belt.  This  zone  runs  the  length  of  the  county  along  and 
just  outside  the  county  line.  It  extends  enstward  beyond  the  Klamath 
and  some  miles  up  the  Salmon  River. 

High  gravels  have  been  deposited  at  many  places  on  the  eroded 
peneplain  at  elevations  approximating  2000  feet.  Such  deposits  are 
best  seen  on  French  Hill,  between  the  South  and  Middle  forks,  but 
similar  bodies  have  been  hydraulicked  at  Big  Flat,  Bald  Hills  and  else- 
where. These  deposits  are  typically  thin,  and  of  such  age  that  their 
equivalence  with  the  oldest  of  the  Salmon  River  deposits  is  probable. 
The  newer  deposits  of  gravel  on  the  benches  near  the  present  streams 
have  been  derived  from  these  old  beds.  They  are.  usually  thin  layers 
reaching,  however,  a  maximum  depth  of  25  feet  in  one  case. 

Distribution   of  Platinum. 

Very  little  production  of  platinum  has  been  reported  from  the  stream 
itself,  but  certain  of  its  tributaries  produce  a  very  small  quantity  as  do 
also  the  older  high  gravels  of  French  Hill.  Deposits  of  same  age  as 
the  French  Hill  gravel  have  without  doubt  been  the  source  of  the 


PLATINUM    AND   ALLIED   METALS.  59 

platinnin  found  below  in  the  Sonth  Fork  and  its  laterals.  On  the 
^riddle  Fork  of  Smith  River  there  are  some  areas  of  anriferous  gravels 
wliich  have  been  mined,  and  some  which  have  never  been  tested  on  a 
working  scale.  Certain  of  the  latter  are  held  to  be  too  low  grade  for 
profitable  mining  and  others  carry  too  great  an  overburden. 

The  Elkhorn  mine  at  the  mouth  of  Patrick  Creek  "has  been  mentioned 
;is  a  platinum  producer,  but  as  far  as  could  be  learned,  the  property 
has  made  little  production  of  gold  and  none  of  platinum.  It  has  been 
idle  for  years  except  for  occasional  short-lived  efforts.  The  gravel  is 
low  grade  in  gold.  The  latest  work  has  been  on  the  second  bench  above 
the  river,  near  the  mouth  of  the  creek.  There  is  a  six  foot  bank  of 
gravel  carrying  Tieavy  boulders,  and  having  a  steep  serpentine  bed- 
rock. An  elaborate  undercurrent,  evidently  installed  recently,  con- 
tained considerable  black  sand.  This  sand  carried  a  few  colors  of  fine 
.uold,  but.  uo  platinum  was  present.  The  holdings  of  this  company 
originally  comprised  2560  acres. 

The  George  Washington  placer  claims  and  the  Monkey  Creek  mine 
(omprise  -480  acres  along  Monkey  Creek  near  its  mouth.  The  former 
has  never  been  worked  beyond  the  prospecting  stage,  and  the  latter 
has  ])een  ground-sluiced,  but  no  platinum  has  been  reported.  It  is 
stated  that  platinum  can  be  panned  sparingly  in  gravel  near  the  mouth 
of  Siskiyou  Fork.  There  is  little  possibility  of  mining  being  resumed 
in  tliis  locality  as  it  is  believed  that  the  Chinese  worked  the  best  of  the 
ground  in  early  days. 

Coming  downstream,  the  river  canon  opens  upon  an  extensive  gravel 
flat  as  we  approach  Gasquet  and  Adams  Stage  stations.  Several  hun- 
dred acres  here  have  never  been  mined  but  prospecting  has  shown  it 
to  be  low  in  gold  content.  The  land  is  farmed  now  and  there  is  little 
l»robability  of  any  mining  there.  Two  and  a  half  miles  below  Adams 
Station  considerable  hydraulic  mining  has  been  done  by  Geo.  Cook  on 
lienches  on  both  sides  of  the  river.  The  gravel  is  on  'diorite'  bedrock 
and  has  a  depth  of  about  25  feet.  There  was  a  total  yield  of  slightly 
over  two  ounces  of  platinum  with  a  moderate  quantity  of  gold.  No 
work  has  been  done  here  for  years  and  there  is  not  apt  to  be  any 
renewal  of  operations  this  season. 

At  tlie  mouth  of  IMyrtle  Creek  and  extending  along  the  river  and 
up  the  creek  for  possibly  a  mile,  are  twenty-seven  mining  claims  for- 
merly held  by  the  Myrtle  Creek  Placer  Mining  Company,  now  defunct. 
The  deposit  is  on  benches,  tlie  first  of  which  is  only  a  few  feet  above  the 
present  stream.  The  gravel  and  overburden  form  a  bank  nearly  a 
hundred  feet  high  but  the  values  are  stated  to  be  on  and  within  two 
feet  of  the  bedrock.  No  work  is  at  present  being  carried  on  in  this 
bench  gravel.     Some  attempts  were  made  to  work  it,  but  the  recovery 


60  CALIFORNIA   STATE   MINING   BUREAU. 

is  reported  to  have  been  insufficient  to  pay  for  handling  the  immense, 
practically  barren  overburden.  The  gravel  is  medium  sized  with  a 
streak  of  blue  gravel.  There  is  a  stratum  of  very  tightly  cemented 
gravel  on  portions  of  the  bedrock  in  these  claims.  The  bedrock  is 
serpentine.  The  contact  betM'een  serpentine  and  diorite  crosses  Myrtle 
Creek  a  mile  and  one-half  above  the  mouth  and  crosses  Smith  River 
one-fourth  of  a  mile  above  South  Fork. 

The  shallow  placer  diggings  in  the  bed  of  ]\Iyrtle  Creek  have  proven 
very  rich  in  coarse  gold.  The  largest  nugget  taken  here  was  reported 
worth  $1200  and  the  ground  is  said  to  have  paid  $100  a  day  to  a  man. 
Even  at  this  late  date,  the  miner  in  charge  of  operations  claims  to  be 
making  good  wages.  The  creek  bed  is  being  sluiced,  great  care  being 
taken  to  clean  the  serpentine  bedrock  thoroughly.  A  'self -shooter'  is 
turned  loose  at  intervals  in  the  creek  and  a  No.  3  giant  is  also  used  to 
loosen  up  the  gravel  but  not  in  driving.  Three  men  are  employed.  The 
gold  obtained  is  uniformly  coarse  and  roundish,  showing  little  erosion. 
No  platiniim  has  been  observed  in  the  clean-ups  from  the  creek  but  it 
is  said  to  be  present  in  the  bench  gravel.  The  source  of  the  coarse  gold 
is  probably  in  pockets  along  the  locus  of  tlie  serpentine-diorite  contact; 
it  is  claimed  in  fact,  that  the  contact  marks  the  limit  of  the  coarse  gold 
in  going  up-stream.  A  former  report^  stated  that  "the  black  sands 
carry  platinum  in  considerable  quantity."  This  could  not  be  sub- 
stantiated, Imt  the  amount  of  bench  gravel  mined  was  apparently  too 
small  to  permit  any  judgment  of  the  platinum  content.  Considerable 
panning  here  by  the  writer  failed  to  show  platinum. 

On  the  opposite  side  of  the  river  in  the  area  bordering  the  south  bank 
of  the  South  Fork,  is  the  Nels  Christensen  hydraulic  mine.  There  are 
two  benches  of  gravel.  The  first  bench  is  about  twenty  feet  above  the 
present  river.  The  face  shows  six  feet  of  gravel  containing  very  heavy 
boulders.  The  gravel  is  made  up  principally  of  fine-grained  igneous 
rocks  both  acid  and  basic  and  the  big  boulders  are  all  that  distinguish 
it  from  tlie  other  bench  gravels  in  the  district.  It  is  loose,  and  lies  on 
a  serpentine  bedrock.  The  owner  claims  to  be  able  to  make  little  better 
than  wages  in  this  ground,  which  he  works  a  short  time  each  winter. 
He  has  never  made  any  recovery  of  platinum,  but  the  metal  was  panned 
by  the  writer  in  the  sluice  and  called  to  the  attention  of  the  owner  who 
planned  to  save  it.  The  proportion  of  platinum  to  gold  is  small  and 
the  grains  of  the  former  are  very  fine.  There  are  174  acres  in  this 
property,  most  of  which  is  bench  gravel  which  is  being  farmed.  These 
benches  may  represent  former  levels  of  the  South  Fork,  which  at  present 
enters  the  other  branch  of  the  river  farther  up-stream  through  a  steep 
rock-cut  canon  about  thirty  feet  deep.     If  this  is  the  case,  the  platinum 


^Cal.    state  Min.   Bur.     Mines  and  Mineral  Resources  of  Del  Norte  County,   1915  ; 
also  Report  XIV,  p.  375. 


^ 


PLATINUM    AND   ALLIED   METALS.  61 

is  no  doubt  referable  to  higli  gravels  which  occur  at  several  places  on 
the  South  Fork  watershed. 

Turning  now  to  the  South  Fork  of  Smith  River,  we  find  that  con- 
siderable mining  has  been  carried  on  along  the  stream  near  the  mouths 
of  the  different  tributaries. 

Jones  Creek,  a  tributary  entering  from  the  north,  was  several  years 
ago  the  scene  of  a  sad  disappointment  for  a  company  of  French  people. 
They  were  attracted  by  the  noticeable  amount  of  a  heavy  grayish  metal 
which  they  found  when  prospecting  the  gravel.  They  were  led  into  the 
belief  that  the  metal  was  platinum  and  they  became  so  enthused  that 
they  made  a  considerable  investment  in  plant.  Local  history  has  it 
that  they  did  not  discover  their  mistake  until  they  attempted  to  market 
their  first  clean-up  and  found  it  valueless.  The  name  of  the  disappoint- 
ing metal  is  not  recorded,  but  it  may  have  been  either  awaruite  or  iron. 
•  The  Big  Flat  deposit  lies  at  an  elevation  of  2160  feet  on  the  ridge 
between  Jones  and  Hurdy  Gurdy  Creeks.  Old  reports^  indicate  con- 
siderable activity  here  prior  to  1889,  and  the  production  of  coarse  gold 
pieces  worth  $3  to  $5  common.  The  last  operators  were  Chinese,  who 
worked  the  property  till  1906.  It  is  said  to  have  yielded  a  good  gold 
return,  but  there  is  no  record  of  platinum  there.  This  deposit  has  a 
slate  bedrock.  Local  people  have  been  holding  the  ground  by  location 
for  years,  but  have  done  no  mining.  Prospecting  for  gold  and  plati- 
num was  going  on  in  October,  1917,  at  the  mouth  of  Ilurdj^  Gurdy 
Creek.  A  prospector  told  the  writer  that  in  1904  he  made  a  sensational 
find  of  platinum  in  gravel  there,  and  had  returned  but  recently  to  see 
if  he  could  not  rediscover  it.  His  work  had  given  no  positive  results 
up  to  the  time  of  the  writer's  visit. 

Haines  Flat,  on  the  divide  between  Gordon  Creek  and  Coon  Creek, 
has  a  narrow  gravel  deposit  trending  southwest.  There  has  been  no 
recent  attempt  to  work  here,  and  platinum  was  not  reported.  Years 
ago  an  attempt  to  mine  the  deposit  resulted  in  disaster  when  a  miscalcu- 
lation was  made  in  the  depth  of  an  expensive  bedrock  cut. 

From  the  mouth  of  Rock  Creek  to  Coon  Creek,  about  three  and  one- 
half  miles  as  the  river  flows,  there  are  small  areas  of  bench  gravels  at 
intervals  along  the  river.  These  are  of  later  origin  than  the  high 
gravels  and  are  near  the  present  river,  where  the  canon  is  more  spacious 
than  the  box-like  trench  to  which  tlie  South  Fork  is  usually  confined 
in  this  region.  The  canon  sides  are  steep  and  are  heavily  covered  by 
brush  and  trees  here,  so  that  there  nuiy  easily  be  sections  of  bench 
gravels  completely  covered  by  slides  and  vegetation.  Three  benches, 
15  to  25  feet  apart,  have  been  noted.  The  lowest,  as  exposed  opposite 
the  mouth  of  Coon  Creek,  shows  serpentine  bedrock,  and  there  are  lenses 


'Cal.  state  Min.  Bur.,  Report  XI,  p.  196;  XIII,  p.  127. 


62  CALIFORNIA   STATE   MINING   BUREAU. 

of  tightly  cemented  eonglonierate  frozen  to  it  in  places.  This  gravel 
pans  some  gold  and  platinnm.  The  gravels  of  these  benches  have  been 
mined  in  a  small  way  by  drifting  and  sluicing.  Locations  were  recently 
filed  on  1000  acres  here  and  in  October,  1917,  preparations  were  under 
way  to  begin  hydraulic  mining.  Trouble  has  heretofore  been  experi- 
enced in  saving  fine  gold,  as  this  section  of  the  South  Fork  carries  a 
high  percentage  of  black  sand,  attributable  to  the  erosion  of  serpentine. 
Mr.  Gordon  Land,  in  charge  of  work  for  the  new  company,  planned 
to  meet  this  by  using  a  magnetic  separator  of  his  own  invention.  He 
claims  that  the  practical  value  of  this  apparatus  has  been  fully  proven 
This  property  ought  to  develop  into  the  principal  gold  and  platinu 
producer  of  the  county.  However,  no  production  was  made  up  to  the 
beginning  of  1919  so  far  as  could  be  learned. 

High  gravel  on  the  Bald  Hills,  west  of  the  mouth  of  Coon  Creek, 
formerly  yielded  wages.  This  deposit  is  about  six  feet  thick  and  at  an 
elevation  of  2050  feet.  Similarly,  Lower  Coon  Mountain  between  Coon 
Creek  and  Craigs  Creek  was  Morked.  but  has  been  idle  since  1900. 

French  Hill  is  a  portion  of  the  Klamath  peneplain  between  the  South 
and  Middle  Forks  of  Smith  River.  It  is  nearly  level  on  top,  having 
an  average  elevation  of  2000  feet  for  about  four  miles  east  and  west, 
with  a  maxinuim  width  of  two  miles.  Serpentine  and  cliorite  mantle 
the  north  and  soutli  sides  of  the  mountain.  The  exact  character  of 
the  bedrock  in  some  of  the  hydraulic  pits  could  not  be  determined  as 
weathering  had  profoundly  altered  it.  Copper  prospectors  who  have 
explored  the  north  slope  above  Adams  Station,  have  found  only  small 
bunches  of  high  grade  secondary  copper  ores  and  heavy  black  iron 
oxides  in  the  serpentine.  Valuable  chromite  mines  were  operated 
during  1917  and  1918  on  tlie  south  side  in  a  diorite-serpentine  contact. 
The  old  surface,  now  covered  with  gravel,  sloped  gently  south  and  west. 
Small  mines  have  been  opened  in  the  gravel  at  several  places,  but  the 
principal  workings  are  those  of  J.  M.  Darnell.  He  works  two  pits  with 
giants  and  has  been  making  a  small  annual  recovery  of  platinum  for 
many  years.  The  northeasterly  opening  shows  the  bedrock  covered  by 
only  two  to  four  feet  of  gravel,  thinning  to  the  northeast.  The  other 
pit,  one-third  of  a  mile  southwest,  has  a  face  of  gravel  20  feet  thick,  with 
two  feet  of  blue  gravel  near  the  bottom  apparently  carrying'  the  best 
values.  There  is  said  to  be  an  ounce  of  platinum  for  about  each  .$1000 
in  gold.  It  is  all  very  finely  comminuted.  No  analysis  of  it  was 
obtainable. 

South  of  French  Hill,  Craigs  Creek  and  its  tributaries  have  eroded 
deep  trenches  to  keep  pace  with  the  South  Fork.  The  gravels  accumu- 
lated in  the  creek  trough  are  similar  in  character  and  age  to  the  low 
gravels  along  the  river,  but  have  apparently  proven  richer  in  l)oth  gold 


le 


;  PLATINUM    AND    ALLIED    METALS.  63 

and  platinum.  They  are  evi(lentl\-  reconcentrated  directly  from  the 
French  Hill  deposit.  The  sketch  map  of  the  geology  shows  that  the 
creek  crosses  alternating  areas  of  diorite  and  serpentine.  Some  low 
■  benches  have  been  cut  above  the  present  stream.  Craigs  Creek  was 
mined  by  the  pioneers,  who  left  only  small  areas  untouched.  The 
operations  of  the  present  owner  have  proven  profitable  whenever  he 
could  find  such  virgin  ground.  One  such  place  was  on  the  creek  two 
'  miles  above  Kaus'  cabin  and  six  miles  from  South  Fork.  Here  the 
i  creek  bed,  which  is  in  serpentine,  was  cleaned  for  a  length  of  200  yards 
and  a  width  of  20'  to  40'.  The  gravel  was  only  one  to  three  feet  deep. 
At  the  same  time  a  small  area  on  the  bench  above  the  creelv  was  cleaned. 
The  total  yield  was  25  ounces  of  gold  and  2:^  ounces  of  platinum.  The 
largest  nugget  of  platinum  weighed  only  five  grains.  Kaus  believed 
the  bench  gravel  was  richer  in  platinum  and  that  the  amount  of  plati- 
num increased  up-stream.  Several  pans  taken  by  the  writer  from  the 
uench  gravel  gave  five  or  six  colors  of  gold  and  half  as  many  very  small 
platinum  colors  each,  ])ut  the  serpentine  itself  yielded  nothing.  This 
place  was  only  a  short  distance  from  the  Tyson  chromite  mine,  which 
deposit  is  on  a  contact  of  true  diorite  and  serpentine. 

A  miner  who  worked  on  Craigs  Creek  twenty  years  ago  states  that 
the  yield  was  good,  the  largest  gold  nugget  found  being  worth  $92, 
with  one-fourth-ounce  pieces  common.  Platinum  was  seen  in  consider- 
able quantity  but  never  saved.  Just  west  of  Kaus'  cabin,  and  about 
50  feet  above  the  present  stream,  a  tributary  entered  from  the  north. 
The  gravel  in  it  is  coarse,  entirely  fine-grained  igneous  (locally  called 
'diorite')  and  on  a  'diorite'  bedrock.  It  yielded  coarse  gold  but  no 
platinum. 

Origin  of  the  Platinum. 

From  what  has  been  written  above,  it  is  seen  that  platinum  occurs  in 
tiie  older  gravels  which  have  been  deposited  as  often  as  not  on  the 
eroded  surface  of  the  serpentine.  This  has  led  to  a  confusion  of 
thought  on  the  part  of  some  miners,  who  cite  the  fact  as  conclusive 
evidence  that  the  platinum  could  not  have  come  from  the  serpentine. 
In  passing  this  judgment  they  fail  to  visualize  the  great  planing  down 
carried  on  by  the  Smith  River.  The  erosion  of  serpentine  has  been 
pronounced  and  the  deposition  and  reconcentration  of  gravels  has  been 
coincident  with  it.  All  the  platinum  in  Smith  River  basin  appears  to 
have  travelled  considerable  distances.  The  gravel  resembles  in  mineral 
character  the  Klamath  River  terrace  deposits  and  the  two  were  derived 
chiefly  from  equivalent  formations.  The  remnants  of  the  old  pene- 
plain, which  stand  at  elevations  of  8500  to  5000  feet,  give  a  good  idea 
of  the  erosion  in  Quaternary  times. 


64  CALIFORNIA   STATE   MINING   BUREAU. 

The  Smith  River  terraces  are  not  as  well  or  regularly  developed  as 
on  the  neighboring  rivers;  and  conditions  of  rainfall  and  deposition 
have  been  different,  but  the  series  as  a  whole  is  contemporaneous.  The 
resources  of  this  basin  in  gold  and  platinum  metals  are  much  less 
promising  than  on  the  Trinity  and  Salmon,  and  the  deposits  are  very 
small  in  comparison.  The  inaccessibility  of  the  country  has  retarded 
development  seriously  and  will  continue  to  operate  to  the  disadvantage 
of  those  interested. 

KLAMATH  RIVER. 


.1 


Platinum  is  recovered  in  hydraulic  and  drift  mining  operations  along 
the  Klamath  from  Weitchpec,  just  below  the  mouth  of  the  Trinity,  to 
Hamburg  Bar.  It  is  known  to  occur,  but  is  not  saved  on  a  commercial 
scale,  at  practically  every  other  camp  on  the  Klamath. 

At  Weitclipec,  the  metal  is  gained  from  hydraulicking  the  first  bench 
just  above  the  water.  There  is  a  slate  Ijcdroek  on  this  claim  and  the 
rough  upturned  edges  of  this  formation,  crossed  nearly  at  right  angles 
by  the  river,  have  proven  a  good  riffle  for  the  precious  metaLs.  The 
ground  is  so  near  the  water  tliat  a  rise  of  a  few  feet  in  the  river  stops 
work  in  the  mine.  The  Klamath  in  rainy  weather  is  apt  to  rise  as  much 
as  two  feet  in  an  hour  and  has  risen  at  Weitchpec  as  much  as  75  feet 
above  low-water  mark.  The  lower  end  of  the  sluice  boxes  are  in  the 
water  in  summer  and  have  to  be  moved  with  the  beginning  of  the  rainy 
season.  The  owner  plans  to  move  his  sluices  to  higher  ground  and  pipe 
up  to  them.  The  gold  varies  in  size  from  flour  to  -|"  and  is  nearly  all 
flaky,  although  some  of  it  shows  rough  edges,  suggesting  its  derivation 
from  the  quartz  seams  which  cut  the  slate  in  great  numbers  along  the 
strike.  The  platinum  grains  are  uniformly  fine,  varying  in  size  from 
dust  to  two  pin  heads,  and  exhibit  differences  which  indicate  two 
sources.  That  portion  of  it  which  comes  from  the  Trinity  River  retains 
its  crystal  shape  and  is  prevailingly  coarser  than  the  Klamath  River 
platinum  which  is  more  water-worn  and  flaky. 

The  yield  of  platinum  from  this  property  is  noticeably  higher  than 
from  mines  on  the  Klamath  above  the  junction  with  the  Trinity.  This 
is  due  not  only  to  the  greater  richness  of  the  Trinity  basin  in  platinum 
metals,  but  to  the  ideal  trap  which  the  slate  bedrock  forms.  The  gravel 
on  this  lowest  bench  is  coarse,  carrying  boulders  occasionally  as  large 
as  3  feet  in  diameter,  and  has  a  maximum  thickness  of  30  feet.  There 
is  a  second  bench  directly  above  it  not  considered  as  good  ground  as 
the  first.  Values  are  reported  to  be  almost  entirely  upon  and  within 
3  feet  of  bedrock. 

Going  up  the  Klamath  from  Weitchpec,  the  next  mining  properties 
are  the  Klamath  River  mine  and  two  small  adjacent  properties  situated 


PLATINUM    AND   ALLIED    METALS.  65 

Oil  the  river  abont  'A  miles  above  Weitchpec.  The  sides  of  the  eanoii 
here  are  so  steep  that  one's  first  impression  when  h)oisinti'  aci'oss  the 
river  is  of  looking  at  a  painting.  The  benches  are  relatively  narrow 
and  the  grade  of  the  hillside  ecpials  the  angle  of  repose,  so  that  debris 
is  constantly  sliding  into  the  hydranlie  workings  and  obliterating  the 
(iitehes  and  finmes  if  they  are  in  its  path.  This  condition  is  intensified 
by  the  character  and  condition  of  the  conntry  rock.  The  latter  is  badly 
broken  mica  schist.  It  slides  down  into  the  workings  at  times  in  huge 
blocks  which  require  blasting.  The  Klamath  River  mine  has  produced 
considerable  gold  from  the  lower  bencli,  but  mining  at  present  is  on  the 
upper  ground.  The  gravel  is  rather  coarse  and  the  gold  prevailingly 
line.  Platinum  metals  occur  with  it  in  the  ratio  of  about  one  ounce  to 
.^i3',000  gold.  The  bedrock  in  these  mines  resembles  closely  the  mica 
schists  of  the  Mother  Lode.  It  carries  a  small  amount  of  gold  which  is 
readily  distinguished  from  the  placer  gold  of  the  gravels  by  its  rough- 
nes-s.  The  platinum  has  associated  with  it  a  considerable  ([uantity  of 
metal  which  looks  like  the  platinum  but  is  of  inferior  specific  gravity 
and  is  highly  magnetic.  Work  was  planned  in  1917  on  high  ground 
which  consists  principally  of  coimtry  rock  slide  material  with  very  little 
gravel.  There  is  a  great  deal  of  black  sand  in  the  mines  along  the 
Klamath  and  this  becomes  a  serious  obstacle  in  recovering  the  fine  gold 
and  platinum.  An  undercurrent  is  to  be  installed  at  the  Klamath  River 
mine  in  order  to  make  a  higher  saving  of  these  fine  values. 

At  the  adjoining  Florence  mine,  which  is  next  above  the  Klamath 
River  mine,  the  conditions  are  the  same,  but  work  is  done  on  a  small 
scale  and  as  far  as  known  no  platinum  has  been  marketed.  Opposite 
these  properties  is  the  Cavanaugh  mine  where  mining  in  a  small  way 
is  carried  on.     Platinum  metals  in  very  small  quantity  are  found  here. 

Reference  to  the  table  of  assays  will  show  that  the  percentage  of 
platinum  in  the  material  from  this  district  is  very  low,  and  of 
osmiridium,  very  high.  The  material  might  properly  be  called 
osmiridium  as  these  combined  metals  make  up  72%  and  the  platinum 
only  25%  of  the  mixture.  As  far  as  known,  it  has  not  yet  been  deter- 
mined whether  the  three  metals  form  an  alloy,  or  are  associated  as 
mixed  grains  of  platinum,  osmiridium  and  platiniridium. 

Between  Weitchpec  and  Orleans  ])latinum  metals  have  been  men- 
tioned as  occurring  at  different  proiiei'ties  which  are  now  either  idle  or 
working  on  such  a  small  scale  that  platinum  production  is  entirely 
negligible. 

The  Salstrom  mine,  located  one  and  a  half  miles  west  of  Orleans, 
has  yielded  three  ounces  of  platinum  in  six  years  past.  To  procure 
this  small  quantity  an  area  of  approximately  two  acres  has  been  mined 
to  a  maximum  depth  of  30  feet.     No  undercurrent  has  been  used  here 

5—46903 


66 


CALIFORNIA    STATE    MINING   BUREAU. 


and  the  opinion  of  the  owner  is  that  he  lias  been  saving  only  10%  of 
the  platinnm  metals.  lie  has  no  definite  basis  for  this  figure,  but  there 
is  no- reason  for  doubting  that  a  considerable  loss  of  fine  flaky  platinum 
occurs,  as  a  big  head  of  water  is  used  and  the  giant  works  close  to  the 
box  in  driving.  Mining  on  this  property  is  limited  to  an  annual  season 
of  about  seven  weeks,  because  of  scarcity  of  water.  The  gravel  is  easy 
to  mine,  being  of  small  size  with  few  rocks;  and  it  is  ideally  located. 
There  is  in  places  an  overl)urden  of  from  30'  to  60'  which  is  considered 
to  be  devoid  of  values.  The  bedrock  is  mica  schist,  dipping  gently  south- 
east. The  gold  output  is  very  satisfactory  and  there  is  a  reserve  acreage 
of  gravel  which  will  permit  hj^draulic  mining  for  a  long  period.    There 


Photo  No.  4.     The   Orleans    Basin,    Klamath   River,   Humboldt   Coimty. 

is  in  addition  an  area  of  about  60  acres  of  possible  dredging  ground 
on  this  property  as  mentioned  elsewhere  in  this  report. 

There  are  at  the  present  time  no  important  mining  operations  going 
on  in  the  immediate  neighborhood  of  Orleans.  A  great  deal  of 
hydraulieking  has  been  done  in  the  Orleans  Basin  and  there  remains 
tliere  an  immense  acreage  of  high  bench  gravels  and  low  river  bars. 
This  area  is  to  be  classed  as  a  possible  resource  rather  than  a  present 
producer  and  is  accordingly  taken  up  in  another  portion  of  this  paper. 

The  Bondo  mine  and  a  few  other  hydraulic  properties  which  lie  on 
the  Klamath  as  one  travels  upstream  from  Orleans  are  worked  each 
winter,  but  there  is  no  platinum  marketed  from  them  as  far  as  known, 
although  it  has  been  found  in  the  concentrates  from  several  mines. 
The  season  is  short  because  of  scanty  watier  supply. 


I  PLATINUM    AND   ALLIED   METALS.  67 

Seven  miles  above  Orleans  at  the  Rosalina  mine  ou  the  northwest 
ank  of  the  river,  platinnm  has  been  recovered  in  small  quantity,  but 
lining  has  been  practically  suspended  for  several  years.  The  canon 
f  the  Klamath  is  very  steep  here  and  the  country  rock  is  principally 
3rpentine.  Whenever  piping  has  been  attempted,  tlie  country  rock 
as  slid  in,  covering  the  gravel  and  making  it  necessary  to  pipe  off  an 
ndless  supply  of  barren  material  before  any  pay  gravel  can  be  reached, 
'his  has  led  the  owner  to  attempt  stripping  the  gravel  back  to  a  point 
'here  sliding  will  be  less  bothersome.  A  sample  of  sand  residue  from 
le  clean  up  of  this  mine  was  assayed  by  the  U.  S.  Geological  Survey 
od  gave  a  high  return  in  gold  and  platinum. 

Just  below  the  mouth  of  the  Salmon  River  on  the  southeast  bank  of 
ic  Klamath,  drift  mining  is  being"  carried  on  because  the  position  of 
le  gravel  is  too  low  to  permit  piping  and  dumping.  There  is  a  bed 
f  gravel  sixty  feet  thick,  Avhich  is  said  to  be  good  pay  through  its 
atire  depth,  but  of  course  the  drifting  takes  only  the  dirt  near  bed- 
Dck,  which  has  yielded  as  liigh  as  $7  a  cubic  yard.  The  ground  can 
Qly  be  worked  during  low  water  from  July  to  November.  The  owner 
sports  the  platinum  content  to  run  about  one  ounce  for  each  one 
lousand  dollars  gold.     Production  to  date  has  only  been  nominal. 

Two  and  one-half  miles  above  the  mouth  of  the  Salmon,  on  the 
pposite  bank  of  the  Klamath,  platinum  has  been  noted  in  small 
uantity  from  time  to  time  at  the  Ten  Eyck  mine^  but  was  never  saved 
)r  sale  before  the  season  just  past.  A  small  shipment  was  made  in 
'ctober,  1917.  The  analysis  indicated  8^%  platinum  and  91§% 
5miridium.  Two  benches  of  gravel  have  been  mined  on  this  property 
Qd  there  is  a  third  higher  bench  which  has  not  been  piped.  The 
►west  bench  is  about  50  feet  above  low  water.  The  bedrock  here  is 
ate  and  the  gravel  is  loose.  While  there  is  considerable  overburden, 
,  is  not  as  troublesome  as  at  properties  farther  down  the  river,  because 
le  canon  side  is  graded  down  here  considerably  by  the  waters  of  Ten 
lyck  Creek.  The  gold  is  coarse  and  the  property  a  good  producer, 
'he  second  bench  lies  300  feet  above  the  first  and  has  a  serpentine 
edrock  with  a  finer  average  run  of  gravel.  The  owner  states  that 
ight  years  ago  he  did  some  mining  on  this  upper  bench  which  yielded 
lual  quantities  of  fine  gold  and  platinum.  Work  there  was  suspended 
ecause  tailings  dumped  from  this  upper  ground  would  cover  up  the 
;ill  unmined  portion  of  the  lower  bench.  Twelve  pans  of  dirt  washed 
rom  this  gravel  showed  two  colors  of  a  silver  gray  metal  which  was 
ighly  magnetic  and  inferior  in  luster  and  specific  gravity  to  most 
lacor  platinum.  It  is  classed  as  magnetic  iron  pending  further 
samination  of  similar  grains  found  in  the  concentrates  of  the  Klamath 
[i\  er  mine.     If  it  contains  platinum  it  must  be  low  grade.     (Refer  to 


68  CALIFORNIA    STATE    MINING   BUREAU. 

analysis  above.)  The  serpentine  extends  westward,  np  the  slope  giving 
place  to  an  area  of  'diorite'  (meta-gabbro  of  Hershey)  which  is  of 
small  extent  and  is  followed  by  another  extensive  serpentine  area. 
The  present  owner  of  the  Ten  Eyck  has  prospected  the  slope  above  the 
second  bench  and  has  found  many  small  gold  pockets,  which  probably 
owe  their  origin  to  contact  phenomena  around  the  'diorite'  and  ser- 
pentine contact.  The  largest  of  these  pockets  yielded  about  $1400 
in  gold. 

One  mile  and  a  half  above  the  Ten  Eyck  mine  a  small  platinum 
production  was  made  last  season  from  the  Mann  and  Ross  drift  mine. 
The  work  here  is  on  the  lowest  bench,  which  is  some  20  feet  above  low 
water.  The  bedrock  is  slate  and  the  gravel  (juite  coarse,  the  cobbles 
being  chiefly  of  slate,  amphibolite  and  granodiorite.  Drifting  had  to  be 
resorted  to  in  order  to  avoid  the  sliding  overburden,  which  covered  the 
gravel  and  came  into  the  pit  whenever  piping  wa.s  done.  Drifts  total 
460  feet  in  length.  The  gravel  yielded  a  very  satisfactory  gold  return, 
but  the  ratio  of  platinum  to  gold  was  low — about  one  ounce  platinum 
to  $3600  gold.  The  assay  of  this  material  was  not  available,  but  the 
price  paid  indicates  a  higher  percentage  of  platinum  and  less 
osmiridium  than  properties  farther  down  stream. 

Continuing  up  the  Klamath  River,  the  production  of  platinum  is 
observed  to  maintain  a  low  ratio  to  gold.  At  the  Blue  Nose  mine  the 
1916  clean-up  of  platinum  netted  less  than  ten  dollars.  This  mine  is 
18  miles  above  Somes  Bar  and  the  geological  relationship  is  said  to  be 
the  same  as  at  the  Ten  Eyck  mine.  There  is  a  slate  bedrock  in  the 
mine  opening  and  there  are  four  benches  of  gravel.  An  undercurrent 
is  used  only  when  there  is  an  abundance  of  water  and  very  little  pains 
are  taken  to  save  platinum,  which  is  uniformly  fine.  Between  the 
Mann  and  Ross  mine  and  Happy  Camp  the  mining  is  mostly  on  a 
small    scale. 

THE  SALMON  RIVER  DISTRICT. 
Topography  and   Relief. 

There  are  only  two  or  tliree  small  areas  of  arable  land  in  the  basin. 
The  remainder  is  a  jumble  of  mountains  deeply  dissected  by  streams, 
clothed  with  impenetrable  masses  of  brush  for  the  most  part,  and 
carrying  very  little  merchantable  timber.  Except  for  a  few  high 
meadows  in  the  northern  part,  the  district  is  not  good  for  stock  range, 
as  the  growth  of  grass  is  sparse,  even  where  the  surface  is  free  from 
brush. 

The  South  Fork  of  Salmon  takes  its  course  parallel  to  the  Orleans 
Mountains,  a  spur  of  which  trends  southeast  from  the  Klamath  River 
to  the  Sawtooth  Range,  separating  the  Salmon  from  New  River  and 
the  North  Fork  of  Trinity  River  with  a  divide  having  many  peaks 


PLATINUM    AND    ALLIED    METALS. 


69 


Photo  No.  5.     The 


Salmon    Mountains,    looking    east    from    Crapo    Mountain    toward    Mount 
Shasta.     Photo   by    Irving    Eidredge. 


70  CALIFORNIA    STATE   MINING   BUREAU. 

nearly  7000  feet  in  elevation.  This  divide  is  deeply  carved  by  the 
streams  but  shows  remnants  of  the  old  peneplain  surface  in  many  of 
the  long  ridges  Avliich  reach  out  from  the  axis  of  the  divide  toward  the 
river.  A  fine  example  of  this  phase  of  the  topography  is  the  ridge 
between  Methodist  and  Knownothing  creeks.  One  can  walk  here  for 
over  three  miles  along  a  narrow  spur  at  an  elevation  varying  little 
from  3700  feet. 

Between  the  South  Fork  and  the  North  Fork  of  Salmon  lies  the  Blue 
Ridge,  the  summit  of  wbich  averages  about  5000  feet  and  culminates 
in  a  peak  5938  feet  high.  This  slopes  gently  toward  the  South  Fork, 
but  on  the  north  presents  a  steep  front,  cliflP-like  in  places,  with  the 
North  Fork  winding  around  its  base.  The  North  Fork  marks  a 
topographic  boundary  as  sharp  as  the  geologic  contact.  North,  east 
and  south,  tbe  Salmon  IMountains  half  enclose  the  basin  within  a  rough 
gigantic  crescent.  The  higher  ])eaks  of  the  range  are  well  over  7000 
feet  and  the  road  from  Sawyers  Bar  to  Etna  Mills  has  to  climb  by  many 
curves  to  6159  feet  ])efore  it  can  pass  the  barrier.  Tliese  mountains 
are  harsh,  rough,  rocky  piles  stretching  beyond  the  reach  of  vision  in 
a  succession  of  brushy  spurs  often  bare  of  timber.  Cupped  in  such 
rocky  basins  are  the  little  lakes  lying  at  elevations  of  6000  feet  or  more, 
which  give  origin  to  the  Little  North  Fork. 

Drainage  and  Water  Resources. 

The  Salmon  River  drains  a  watershed  of  about  750  square  miles,  being 
bounded  on  the  west  by  the  Orleans  INIountains,  on  the  south  and  east 
by  Trinity  Summit  and  on  the  north  and  east  by  the  Salmon  Mountains 
On  all  sides,  except  northwest  toward  the  Klamath,  the  mountains  are 
high  and  the  Salmon  basin  is  effectually  isolated.  Orleans  Summit  is 
over  6100  feet  high  and  the  chain  on  that  side  exceeds  5000  feet  in  most 
places  till  the  Sawtooth  Range  is  reached,  where  the  highest  point, 
Thompson  Peak,  reaches  an  elevation  of  8936  feet.  The  Salmon  Moun- 
tains oifer  a  barrier  which  is  deeply  drifted  with  snow  in  winter,  and 
in  severe  seasons  the  mail  has  to  be  carried  in  by  men  on  snowshoes. 

The  North  Fork  of  the  Salmon  rises  in  the  Salmon  Mountains  and 
after  flowing  north,  east  and  south,  finally  breaks  out  of  the  high  moun- 
tains and  receives  Russian  Creek,  one  of  its  chief  branches,  a  few  miles 
cast  of  Tanners  Peak.  Here  it  turns  west.  Its  other  main  tributary 
is  the  Little  North  Fork,  a  beautiful  stream  whose  upper  course  is  little 
known.  This  enters  North  Fork  from  the  north  five  miles  below 
Sawj^ers  Bar. 

The  South  Fork  has  two  main  branches,  one  flowing  southwest  and 
the  other  northwest  from  the  perpetual  snow  banks  of  Thompson  Peak. 
From  their  junction  at  Cecilville  the  stream  flows  northwest,  receiving 


PLATINUM    AND   ALLIED   METALS. 


71 


the  drainage  from  the  Orleans-Trinity  summits  on  the  southwest  and 
from  the  Blue  Ridge  on  the  northeast. 

Both  forks  and  their  tributaries  have  steep  grades.  From  tlie  peak 
near  Summit  mine,  elevation  6320  feet,  across  the  South  Fork  to  the 
top  of  Blue  Ridge,  5938  feet,  is  ten  and  one-half  miles,  with  the  South 
Fork  at  an  elevation  of  1500  feet.  A  profile  across  the  North  Fork 
from  the  summit  of  Blue  Ridge  to  the  summit  above  Garden  Gulch, 
G777  feet  high,  is  only  five  and  one-fourth  miles,  with  the  river  flowing 
in  a  deep  notch  1700  feet  above  sea  level.     The  North  Fork  shows  a 


Photo   No.   6.      Hancock   Lake,    elevation   6317   feet.     Type   of  snow-fed   basins  which   lie  at  the 

sources  of  streams  in  the  Salmon  Mountains. 

grade  of  about  51  feet  a  mile  from  Sawyers  Bar  to  forks  of  Salmon, 
which  is  11  feet  a  mile  more  than  on  the  South  Fork.  From  the  con- 
fluence at  forks  of  Salmon,  the  river  turns  northwest  and  holds  a 
crooked  course  over  a  rocky  bed  for  nineteen  miles,  entering  the 
Klamath  at  an  elevation  of  only  about  525  feet,  sliowing  an  average 
grade  of  38  feet  to  a  mile  in  this  distance. 

These  steep  grades  have  favored  the  hydraulic  miner  so  that  he  can 
get  a  six  to  eight  months  water  supply  with  plenty  of  fall  from  a  ditch 
usually  not  over  five  miles  long,  if  he  is  mining  the  lower  deposits.  One 
property  has  a  perpetual  supply  with  a  five  mile  ditch.  The  flow  of  both 
forks  of  the  river  has  been  appropriated  by  companies  operating  near 
their  confluence,  and  hydraulic  properties  at  the  mouths  of  the  principal 
tributaries  farther  up  use  the  main  part  of  the  water  which  enters  the 
lower  courses  of  the  two  forks,  between  Sawyers  Bar  and  forks  of 
Salmon  on  the  North  Fork  and  to  a  considerable  distance  up  the  South 


72  CALIFORNIA    STATE    MINING   BUREAU. 

Fork.  The  water  supply  is  adequate  to  work  the  gravels.  The  streams 
are  perennial  in  flow,  having  their  sonrees  in  springs  where  they  do  not 
reach  back  into  the  region  of  perpetual  snow. 

Geology. 

The  writer  made  the  trij)  up  the  Klamath  on  foot  from  Orleans  to  a 
point  several  miles  above  Somes  Bar.  thence  across  the  Klamath,  back 
to  the  Salmon  and  over  two  spurs  of  the  Orleans  Mountains  to  forks  of 
Salmon.  The  trip  was  in  the  nature  of  reconnoisance,  with  the  idea  of 
surveying  in  a  general  way  the  areas  of  platinum  production,  with  the 
{possibility  of  more  detailed  work  being  done  later.  Therefore,  it  was 
not  possible  to  map  the  areal  geology  in  detail  or  to  make  the  field 
studies  necessary  for  a  proper  correlation  of  details. 

Serpentine  is  prominent  on  the  river  at  Somes  Bar  bridge  and  for 
about  three  miles  upstream.  This  is  the  eavstern  portion  of  the  extensive 
greenstone-serpentine  belt  which  follows  the  Klamath  northward  past 
Happy  Camp,  crosses  into  Oregon  and  extends  westward  into  Del  Norte 
County.  From  the  time  the  trail  leaves  the  river  to  cross  the  moun- 
tains, no  more  serpentine  areas  are  seen.  Diorite,  and  related  porphyry 
('birdseye  porphyry'  of  the  miners)  are  prominent  among  the  igneous 
rocks  of  the  ridges.  No  platinum  has  been  produced  on  this  part  of 
the  Salmon  and  no  mining  is  going  on  there  now.  The  river  flows  in  a 
crooked  box  canon  cut  for  the  most  part  in  amphibolitic  schists,  the 
origin  of  which  may  be  attributed  to  metamorphism  of  the  diorites  and 
similar  rocks  to  the  south. 

Because  of  the  interesting  conditions  noted  in  connection  with  the 
occurrence  of  platinum  on  the  two  forks  of  the  river,  the  writer  spent 
several  days  in  a  study  of  the  region  from  Sawyers  Bar  southwestward 
to  Gilta,  and  from  forks  of  Salmon  to  Black  Bear.  The  geology  was 
noted  here  in  a  general  way.  but  particular  attention  was  given  to  the 
location  of  serpentine  and  to  the  properties  where  platinum  has  been 
found.  The  sketch  map  of  the  areal  geology  indicates  definitely  the 
distribution  of  serpentine,  but  other  formations  are  not  as  precisely 
placed. 

This  region  is  made  up  of  a  great  variety  of  metamorphie  and  igneous 
rocks,  mingled  in  a  complexly  folded  and  faulted  mass  having  a  high 
ridge  with  a  northeast  trend.  It  is  called  the  Blue  Ridge.  Its  north 
side  is  steep  enough  to  suggest  a  fault  scarp,  but  the  slope  to  the  South 
Fork  is  gentle. 

Unaltered  sedimentary  rocks  were  not  seen  here.     Rocks  originally 
sedimentary  have  been  altered  by  pressure,  folding  and  the  action  of 
igneous  intrusives.     Probably  the  whole  series  including  both  igneous 


PLATINUM    AND    ALLIED    METALS. 


73 


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PLATINUM    AND   ALLIED   METALS.  73 

vnd  metamorphic  members,  is  the  same  as  described  by  J.  P.  Smith^  to 
the  east  of  this  area  under  tlie  name  of  'greenstone  series.'  He  con- 
sidered the  age  of  that  series  indeterminate,  but  not  later  than  Lower 
Devonian.     Smith's  work  exten(h^d  only  as  far  west  as  Russian  Creek. 

Rocks   Originally   Sedimentary. 

Slate  occurs  as  bedrock  in  several  of  the  hydraulic  mines,  notably 
around  Sawyers  Bar  and  Eddy's  Gulch.  There  is  also  a  small  outcrop 
of  it  on  lower  Knownothing  Creek.  It  occurs  as  one  wall,  and  some- 
times as  both,  in  most  of  the  quartz  mines  in  the  district.  In  the  Black 
Bear  and  Klamath  Mines  it  forms  both  walls  of  deposits  which  occur 
as  lenses  and  stringers,  and  is  often  mixed  with  quartz  as  the  tilling  of 
crushed  zones.  The  Black  Bear  deposit  is  strikingly  similar  to  the 
'stringer  leads'  of  some  ]\Iother  Lode  properties,  but  there  is  no  prom- 
inent cropping  of  quartz  to  correspond  to  the  'bull  quartz'  veins  of 
Calaveras  and  Tuolumne  counties.  Slate  also  occurs  as  hanging-  or 
loot-wall  in  contact  deposits  with  diorite  or  quartz  porphyry  intrusives 
as  the  other  wall.  The  Gilta  Mine  is  an  example.  The  slate  strikes 
northeast  and  dips  southeast  commonly  at  an  angle  of  about  40°,  but 
at  times  reaches  a  60°  dip  because  of  intrusives.  The  uniformity  of 
dip  and  strike  at  properties  rather  far  apart  shows  there  was  originally 
a  long  belt  of  this  rock,  which  has  everywhere  been  broken  and  inter- 
rupted by  the  entrance  of  intrusives.  There  has  not  been  enough  work 
done  to  indicate  the  thickness  of  the  slates,  but  in  the  Sawyers  Bar 
quadrangle  it,  no  doubt,  was  once  continuous  along  the  strike  from  the 
New  River  divide  northeast  to  the  Salmon  Mountain  axis. 

Chert  outcrops  occur  at  several  places,  but  usually  only  as  small 
areas.  The  best  exposure  noted  was  on  the  summit  of  the  nearly  level 
divide  between  Methodist  and  Knownothing  Creeks  at  an  elevation 
near  3500  feet.  Here  one  inch  layers  of  chert  are  interlaminated  with 
thinner  partings  of  calcareous  shale.  The  formation  strikes  N.  20°  E. 
and  dips  45°  NW.  On  the  top  of  the  Blue  Ridge  massive  chert  occurs 
in  place  at  an  elevation  of  5630  feet  (aneroid)  and  strikes  northwest. 
Associated  with  it  are  oxides  of  manganese,  but  all  the  outcrops  seen 
were  too  siliceous  to  be  worth  mining.  Just  west  of  the  slate  belt  at 
•he  Black  Bear  Mine  at  the  roadside,  chert  interbedded  with  thinner 
layers  of  shale  occur,  showing  marked  distortion.  Thus  tliere  are 
evidently  two  characters  of  chert  here,  near  each  other.  The  inter- 
bedded chert-shale  formation  is  strikingly  similar  to  deposits  near  San 
Francisco  Bay  which  Lawson  has  classified  as  INIonterey  (Miocene). 
The  only  other  similar  deposit  was  described  l)y  the  same  writer  in  the 
same  field  as  Franciscan.  The  presence  of  manganese  here  in  associa- 
tion with  the  massive  chert  seems  to  favor  the  supposition  that  this  may 


'Cal.   state  Min.   Bur.     Unpublished  work  on  Geology  of  Central  Siskiyou  County. 


72 


CALIFORNIA    STATE    MINING   BUREAU. 


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PLATINUM    AND    ALLIED    METALS.  73 

and  metamorphic  members,  is  the  same  as  described  by  J.  P.  Smith'  to 
the  east  of  this  area  under  the  name  of  'greenstone  series.'  He  con- 
sidered the  age  of  that  series  indeterminate,  but  not  later  than  Lower 
Devonian.     Smith's  AV(n'k  extended  only  as  far  west  as  Russian  Creek. 

Rocks  Originally  Sedimentary. 

Slate  occurs  as  bedrock  in  several  of  the  hydraulic  mines,  notably 
around  Sawyers  Bar  and  Eddy's  Gulch.  Tliere  is  also  a  small  outcrop 
of  it  on  lower  Knownothing-  Creek.  It  occurs  as  one  wall,  and  some- 
times as  both,  in  most  of  the  quartz  mines  in  the  district.  In  the  Black 
J^ear  and  Klamath  Mines  it  forms  both  walls  of  deposits  which  occur 
as  lenses  and  stringers,  and  is  often  mixed  with  quartz  as  the  tilling  of 
crushed  zones.  The  Black  Bear  deposit  is  strikingly  similar  to  the 
'stringer  leads'  of  some  ]\[other  Lode  properties,  but  there  is  no  prom- 
inent cropping  of  quartz  to  correspond  to  the  'bull  quartz'  veins  of 
(  alaveras  and  Tuolumne  counties.  Slate  also  occurs  as  hanging-  or 
foot-wall  in  contact  deposits  with  diorite  or  quartz  porphyry  intrusives 
as  the  other  wall.  The  Gilta  ]Mine  is  an  example.  The  slate  strikes 
northeast  and  dips  southeast  commonly  at  an  angle  of  about  40°,  but 
at  times  reaches  a  60°  dip  because  of  intrusives.  The  uniformity  of 
dip  and  strike  at  properties  rather  far  apart  shows  there  was  originally 
a  long  belt  of  this  rock,  which  has  everywhere  been  broken  and  inter- 
rupted by  the  entrance  of  intrusives.  There  has  not  been  enough  work 
done  to  indicate  the  thickness  of  the  slates,  but  in  the  Sawyers  Bar 
quadrangle  it,  no  doubt,  was  once  continuous  along  the  strike  from  the 
New  River  divide  northeast  to  the  Salmon  Mountain  axis. 

Chert  outcrops  occur  at  several  places,  but  usually  only  as  small 
areas.  The  best  exposure  noted  was  on  tiie  summit  of  the  nearly  level 
divide  between  Methodist  and  Knownothing  Creeks  at  an  elevation 
near  3500  feet.  Here  one  inch  layers  of  chert  are  interlaminated  with 
thinner  partings  of  calcareous  shale.  The  formation  strikes  X.  20°  E. 
and  dips  45°  NW.  On  the  top  of  the  Blue  Ridge  nuissive  chert  occurs 
in  place  at  an  elevation  of  5630  feet  (aneroid)  and  strikes  northwest. 
A.ssociated  with  it  are  oxides  of  manganese,  but  all  the  outcrops  seen 
were  too  siliceous  to  be  worth  mining.  Just  west  of  the  slate  belt  at 
'he  Black  Bear  Mine  at  the  roadside,  chert  interbedded  with  thinnei- 
layers  of  shale  occur,  showing  marked  distortion.  Thus  there  are 
evidently  two  characters  of  chert  here,  near  each  other.  The  inter- 
bedded chert-shale  formation  is  strikingly  similar  to  deposits  near  San 
FrancLsco  Bay  which  Lawson  has  classified  as  Monterey  (Pliocene). 
The  only  other  similar  deposit  was  described  by  the  same  writer  in  the 
same  field  as  Franciscan.  The  presence  of  manganese  here  in  associa- 
tion with  the  massive  chert  seems  to  favor  the  supposition  that  this  may 


=Cal.   State  Min.    Bur.     Unpubli-sht-d  work  on  Geology  of  Central  Siskiyou  County. 


74  CALIFORNIA    STATE   MINING   BUREAU. 

be  Franciscan.  Some  outcrops  of  limestone  occur  on  the  west  side  of 
Knownothing  Creek  several  miles  above  its  month,  but  time  could  not 
be  taken  to  determine  their  relation  to  the  chert. 

Quartzite  is  reported  from  some  of  the  gold  mines  as  forming  one 
wall  of  contact  depo.sits,  but  it  is  not  of  wide  occurrence  or  particular 
importance  in  this  discussion. 

Altered    Igneous   Rocks. 

Serpentine  outcrops  on  the  North  Fork  drainage  only  in  small  plugs, 
and  is  often  thoroughly  weathered  to  a  reddish  material  forming  a  layer! 
one  or  two  feet  thick.  The  miners  call  this  'porphyry'.  They  often' 
penetrate  it  while  prospecting,  and  find  the  characteristic  greenish  phase! 
of  serpentine  below,  from  Avhich  they  have  drawn  the  erroneous  conclu- 
sion that  serpentine  underlies  the  entire  Blue  Ridge.  The  sketch  map 
shows  that  serpentine  is  widespread  over  the  South  Fork  drainage.  The 
largest  area  forms  the  chief  portion  of  the  basin  of  Niggerville  Creek, 
its  western  contact  crossing  the  South  Fork  diagonally  at  Indian  Creek. 
Here  the  river  has  cut  a  deep  notch  in  it.  The  South  Fork  side  has 
evidently  been  largely  spared  tlie  later  intrusions  and  the  accompanying 
upheavals  which  went  on  along  the  summit  of  Blue  Ridge  to  the  north. 
There  is  probably  a  wide  distribution  of  serpentine  mantled  by  soil 
on  the  South  Fork.  Near  the  Black  Bear  Mine  several  outcrops  of 
serpentine  have  the  aspect  of  sills  which  may  have  been  injected  along 
the  .strike  of  chert  beds.  The  general  impression  gathered  by  observa- 
tion is  that  the  serpentine  has  originally  been  surrounded  by  larger 
areas  of  chert.  The  serpentine  is  deeply  eroded,  but  shows  practically 
no  chromite  content.  The  surfaces  are  usually  light  green,  but  one 
small  area  was  black.  Original  peridotite  occurs  in  one  area  as  a 
prominent  dike. 

A  few  of  the  serpentine  areas  have  yielded  notable  gold  pockets.  The 
largest  one  reported  was  on  Grraham  Gulch  and  is  said  to  have  yielded 
over  $12,000.  A  small  area  at  the  head  of  Jessops  Gulch  near  Sawyers 
Bar  produced  coarse  gold,  some  of  the  nuggets  being  worth  $50.  This 
gold,  no  doubt,  was  originally  deposited  near  contacts  of  intrusive 
diorite  or  similar  rocks  with  the  serpentine.  J.  P.  Smith  mentions  such 
small  deposits  in  the  'greenstone  series'  to  the  east,  as  being  the  result 
of  such  intrusive  action. 

Of  interest  geologically,  but  of  less  importance  in  the  present  paper, 
are  the  other  altered  rocks  of  the  greenstone  series.  These  rocks  include 
members  which  can  not  be  determined  in  the  field  usually,  but  are  of 
widespread  occurrence  in  the  northern  Coast  Range.  They  are  dis- 
tinguished on  one  hand  from  the  deep-seated  granodiorites  and 
granites,  and  from  the  fairly  fresh  unaltered  volcanics  of  Tertiary  age 
on  the  other.  < 


PLATINUM    AND    ALLIED    METALS. 


75 


Granodiorite  forms  the  Salmon  Mountains,  and  every  stream  from 
Bio-  Creek  to  Jackass  Gulch  on  the  north  side  of  the  North  Fork,  carries 
only  granitic  detritus  and  boulders.     Apparently  a  small  boss  of  such 


'^ 


rjr^-^ 


^. 


_5^3l- 


.-V' 


v: 


Photo  No.  7.  Bank  of  pay  gravel  and  overburden.  Bloomer  Mine,  on  Salmon 
River  5  miles  below  Forks  of  Salmon,  Siskiyou  County.  Photo  by  Irving 
Eldredge.     Typical   quaternary   terrace   deposit. 

rock  underlies  Blue  Ridge,  but  it  outcrops  only  in  a  narrow  area  on  the 
summit.     No  other  outcrop  was  observed  south  of  the  North  Fork. 

Prominent  on  the  upper  slopes  is  an  acidic  eruptive  rock,  fine-grained 
almost  to  the  gla.ssy  stage,  showing  principally  quartz  and  feldspar. 


76  CALIFORNIA    STATE   MINING   BUREAU. 

It   covers  the  mountain  sides  with  rough  sharp-edged  blocks  and  is 
apparently  the  j^oiingest  formation  in  the  district. 

Old    River  Terrace   Deposits. 

The  hydraulic  mines  of  the  Salmon  basin,  like  those  of  the  Trinity 
and  Klamath,  are  chietiy  located  in  gravels  on  the  old  river  terraces. 
There  has  not  ])een,  however,  such  an  extensive  development  of  the 
terraces  here.  Hershey^  has  identified  five  old  channels  on  the  South 
Fork  of  Salmon  near  Summerville  and  places  the  highest  at  an  elevation 
of  250  feet  above  the  river.  Thus  it  is  seen  that  the  cutting  action  of 
ihe  stream  has  been  less  pronounced  than  on  neigliboring  rivers  during 
the  Pleistocene.  Hershey  believed  that  a  considerable  arching  of  the 
country  occurred  in  the  late  Neocene-  and  that  a  fold  along  a  north- 
south  axis  crossed  the  present  course  of  the  Salmon  between  the  forks 
of  Salmon  and  the  Klamath,  and  that  this  fold  is  responsible  for  the 
nature  of  the  Pleistocene  Canon  cut  through  it. 

The  old  channels  in  the  district  under  discussion,  reach  their  highest 
elevation  of  300  feet  above  the  South  Fork  on  the  Blue  Ridge  side  at 
the  Nigger  Hill  ]\Iine.  On  the  opposite  bank  bench  gravels  have  been 
hydraulicked  at  several  levels  around  the  mouth  of  Knownothing 
Creek.  Old  deposits  were  laid  down  on  terraces  cut  by  the  latter 
stream  at  different  levels  as  far  as  six  miles  upstream  from  its  mouth. 
These  have  been  mined  in  a  small  scale.  On  both  sides  of  the  North 
Fork  from  the  forks  upstream,  but  more  particularly  as  we  approach 
Sawyers  Bar,  a  similar  series  of  terrace  deposits  have  been  laid  down 
in  old  channels.  The  youngest  of  these  is  only  a  few  feet  above  the 
present  stream.  iNIost  of  the  development  of  these  deposits  has  been 
on  the  north  side  of  the  river,  but  there  is  one  mine  on  the  south  side 
on  the  lowest  bench  at  Sawyers  Bar,  one  on  the  south  l^ank  seven  miles 
downstream  from  Sawyers  Bar,  which  has  an  elevation  of  90  feet  above 
the  stream,  and  another  bench,  evidently  the  highest  and  oldest,  is  200 
feet  vertically  higher,  or  500  feet  on  the  incline.  Terrace  deposits 
were  also  prominently  developed  upstream  beyond  the  Sawyers  Bar 
District  but  proved  not  rich  enough  to  mine  where  they  were  worked  in 
the  vicinity  of  Finley's  Camp. 

Origin   of   Placer  Gold. 

The  origin  of  the  gold  in  the  bench  gravels  on  the  North  Fork  of 
Salmon  was  without  doubt  in  the  series  of  rich  gold-bearing  quartz 
veins  which  traverse  the  slate  and  other  metamorphics.  These  strike 
uniformly  north  and  northeast,  forming  a  belt  which,  in  the  area  con- 
sidered,   has   been    mined   with    profit   from   White's    Gulch    to    Gilta. 


'Hershey,  O.  H.  :  Journal  of  Geology,  Vol.  11,  No.  5. 
=Hershey,  O.  H.  :  Journal  of  Geology,  Vol.   11,  No.   2. 


PLATINUM    AND   ALLIED   METALS.  77 

In  the  left  fork  of  White's  Gulch  the  Lanky  Bob  ^linc  nuuU'  a  Kt><J<l 
yield.  The  owner  of  that  property  subsequently  opened  an  extension 
of  the  same  vein  in  the  right  fork  of  the  gulch,  calling  his  new  mine 
the  Slim  Jim.  The  vein  here  swells  and  pinches  with  considerable 
regularity,  varying  in  width  from  two  inches  to  two  feet,  and  has 
averaged  $20  a  ton.  It  strikes  nearly  north.  Similarly,  the  Uncle 
Sam,  Gold  Ball  and  Klamath  veins  were  all  good  producers.  They  lie 
on  the  North  Fork  side  and  are  crossed  at  right  angk^s  l)y  Eddys, 
Counts  and  Whites  gulches  and  other  tributaries  of  the  North  Fork. 
Hydraulic  miners  in  Eddys  Gulch  recover  now  a  consideralile  (juantity 
of  rough  quartz  carrying  gold  nuggets,  broken  by  erosion  of  such  veins. 
The  placers  on  the  North  Fork  from  a  .short  distance  above  Sawyers 
Bar  to  forks  of  Salmon  are  estimated  to  have  yielded  about  $26,000,000. 
The  famous  Black  Bear  lode,  credited  with  nearly  $3,000,000  produc- 
tion, has  been  opened  on  the  South  Fork  divide,  l)ut  extensions  of  it 
have  no  doubt  contributed  to  the  wealth  of  the  North  Fork.  To  the 
northeast,  beyond  the  area  of  this  report,  some  sensationally  rich  (|uartz 
mines  of  pockety  character  were  opened.  The  Highland  and  Homestake 
have  been  the  chief  producers  among  these.  The  lode  has  been  traced 
both  ways  far  beyond  the  district. 

The  South  Fork  placers  have  been  enriched  in  tlie  lower  part  of  the 
stream  by  erosion  of  vein.s  forming  the  southwesterly  continuation  of 
ihe  same  lode  which  fed  into  the  North  Fork.  Tiie  l)est  producers 
among  the  quartz  mines  opened  on  this  side  were  the  Gilta  on  upi)er 
Knownothing  Creek  and  the  King  Solomon  above  IMatthews  Creek.  At 
the  Bliehigan  Salmon  mine  at  the  mouth  of  the  former  stream,  rough 
nuggets  with  quartz  attached  are  often  found.  The  upper  placers  in 
the  vicinity  of  Cecilville  were  not  as  rich  as  those  from  Matthews  Creek 
downstream.  The  gold  in  that  upsteam  section  probably  came  from  the 
erosion  of  veins  lying  in  a  parallel  belt  passing  through  the  region  of 
Thompson  Peak.  Some  of  these  placers  were  operated  at  a  loss. 
Glaciers  once  occupied  tlie  upper  South  Fork  basin,  moving  from 
Thompson  Peak,  They  deposited  a  good  deal  of  morainal  material  poor 
in  gold.  The  perpetual  snowbanks  on  tlie  north  side  of  Thompson  Peak 
now,  are  reminders  of  these  ice  fields  and  are  sometimes  called  glaciers. 

Occurrence   of   Platinum. 

All  the  evidence  obtainable  in  the  field  leads  to  the  conclusion  that 
the  occurrence  of  platinum  in  the  district  was  coincident  with  the 
presence  of  serpentine.  As  noted  elsewhere,  there  are  only  a  few  small 
areas  on  the  North  Fork  drainage  where  this  rock  has  been  exposed  to 
erosion.  The  principal  outcrops  of  it  are  on  the  South  Fork  side.  The 
field  work  was  not  carried  beyond  ^latthews  Creek,  but  as  far  as  could 
be  learned  that  stream  marks  the  southeast  boundary  of  the  serpentine 


78 


CALIFORNIA   STATE   MINING   BUREAU. 


belt.  Hershey  emphasized  the  absence  of  serpentine  on  the  South  Fork 
from  the  neighborhood  of  Cecilville  for  many  miles  upstream  and 
described  the  few  boulders  of  it  which  he  found  in  the  gravels  there, 
as  erratics,  which  he  believed  came  from  the  Coifee  Creek  (Trinity 
County)  side,  when  the  upper  waters  of  South  Fork  encroached  upon 
and  captured  a  part  of  the  Coffee  Creek  watershed,  during  the  glacial 
epoch/  This  portion  of  the  river  is  of  minor  interest  in  the  present 
discussion,  as  there  is  practically  no  mining  there  and  no  record  of 
platinum  occurrence.  The  point  that  attracts  attention  is  the  fact  that 
platinum  metals  are  produced  in  noticeable  quantity  at  each  of  the 
three  operating  mines  which  are  within  the  serpentine  belt  on  the  lower 


Photo   No.   8     Two   giants  working   under   pressure   of  457    feet.     Red    Hill    (Michigan-Salmon) 

Mine,   South  Fork  of  Salmon  River. 

South  Fork;  but  on  the  North  Fork,  where  dozens  of  properties  have 
operated  for  a  long  period,  and  where  gold  production  was  immense, 
only  a  few  pennyweights  of  these  metals  were  recovered. 

The  Michigan  Salmon  or  Red  Hill  Mine  takes  in  two  and  a  half  miles 
along  the  South  Fork  at  and  near  the  mouth  of  Knownothing  Creek, 
beginning  a  mile  and  a  half  above  the  forks.  In  past  years  the  high 
benches  have  been  worked  but  operations  now  are  confined  to  the  lower 
gravels,  which  are  mined  by  the  aid  of  Ruble  elevators,  as  described 
under  Hydraulic  Mining.  The  ground  handled  is  the  gravel  of  the 
lowest  and  youngest  bench,  only  a  few  feet  above  the  summer  level  of 
the  stream  which  must  partially  flood  it  during  high  water.     A  large 


^Hershey,  O.  H.  :  Journal  of  Geology,  Vol.  11,  No.  5. 


PLATINUM   AND   ALLIED   METALS.  79 

rardage  is  handled  yearly.  Little  attention  has  been  paid  to  platinum 
netals  in  the  past  because  of  their  cheapness,  but  there  is  an  annual 
)roduetion  of  several  ounces.  Probably  a  large  percentage  of  that 
jresent  has  been  lost,  as  no  great  care  seems  to  be  given  to  its  recovery, 
rhe  bulk  of  the  metal  is  in  small  scales  and  nuggets  but  there  are  many 
arger  pieces,  the  biggest  one  saved  weighing  1/8  ounce.  The  small 
;cales  are  bright  but  the  larger  pieces  are  rough  and  coated  with  a 
jlackish  film.  Pits  in  the  nuggets  are  often  filled  with  rusty,  powdery 
joatings  and  one  little  cavity  had  a  bit  of  quartz  in  it  but  this  might 
lave  been  a  grain  of  sand  which  it  had  picked  up.  This  platinum 
showed  little  of  the  smoothing  wear  of  erosion.  The  nuggets  were  of 
i^arious  irregular  and  angular  shapes,  as  if  they  had  come  to  a  resting 
place  in  the  gravel  not  far  from  their  matrix.  An  analysis  of  a  recent 
shipment  of  3.787  ounces  of  the  metal  from  this  property  indicated  only 
3.117  ounce  platinum  and  3.675  ounces  osmiridium.  This  means  that 
it  carries  slightly  under  3%  platinum  and  is  apparently  nearer  to  being 
pure  osmiridium  than  any  other  occurrence  in  California.  It  is  not 
magnetic,  so  could  not  contain  a  ver}^  high  percentage  of  iron. 

The  Nigger  Hill  hydraulic  mine  has  been  opened  on  both  sides  of 
jsjiggerville  Creek  nearly  half  a  mile  upstream  from  the  river.  Two 
benches  have  been  mined.  The  highest  deposit  is  about  300  feet  above 
the  Salmon,  and  is  the  oldest  gravel  in  the  basin.  No  doubt  it  cor- 
responds with  the  oldest  of  the  five  benches  near  Cecilville  which  is 
250  feet  above  the  river.  There  is  a  bank  90  feet  high,  containing  30 
feet  of  gravel  at  the  base,  overlain  by  60  feet  of  a  distinctly  red,  clayey 
overburden.  The  creek  cuts  across  the  terrace,  and  has  eroded  a  deep 
trench  to  keep  pace  with  the  river.  The  heavy  red  clay  overlying  the 
gravel  is  no  doubt  a  torrent  fan  poured  out  delta-fashion  during  stormy 
weather  in  the  days  when  the  creek  entered  the  river  here.  The 
boulders  in  the  gravel  are  medium  sized  and  have  the  appearance  of 
great  age.     The  bedrock  is  also  soft  and  highly  altered,  apparently 


igneous. 


'  Previous  to  last  season  platinum  was  never  saved  at  this  property, 
jthough  considerable  ground  has  been  hydraulicked.  Last  year  several 
JQuggets  of  a  metal  looking  a  good  deal  like  dirty  lead  were  picked  out 
pf  the  box  at  clean-up  time  and  put  aside.  The  man  who  leased  the 
property  recognized  them  as  platinum  metals.  Closer  attention  was 
Ipaid  thenceforth  to  saving  the  material.  The  largest  nugget  was 
jt-eported  to  weigh  one-half  ounce,  and  the  bulk  of  that  saved  was  in 
AUggets  from  a  pennyweight  upward.  Mining  was  done  here  in  a 
i^mall  way  for  about  three  months  with  one  giant  and  a  scanty  water 
;mpply,  but  the  recovery  of  platinum  metals  apparently  equalled  the 
■  iseason's  production  at  the  IMichigan  Salmon  Mine  where  at  least  ten 


80  CALIFORNIA    STATE    MINING   BUREAU. 

times  as  much  ground  was  moved.  This  metal  has  not  been  sold  yet  so 
the  analysis  is  not  obtainable. 

The  Oreutt  hydraulic  mine  is  operated  on  a  small  scale  at  the  mouth 
of  Methodist  Creek,  about  seven  miles  from  forks  of  Salmon.  There  is 
a  small  annual  recovery  of  platinum  here.  The  largest  nugget  recovered 
weighed  slightly  over  four  pennyweiglits.  Serpentine  occurs  promi- 
nently here  and  at  intervals  along  the  creek  basin  to  the  top  of  the 
divide.  Prospectors  who  had  mined  the  upper  creek  with  sluices 
claimed  that  some  ]>latinum  was  always  noticed  in  the  boxes,  but  no 
attention  paid  to  it.  A  nugget  of  platinum  metals  weighing  ^  ounce  is 
said  to  have  been  found  by  a  prospector  near  the  head  of  the  creek 
in  1912. 

On  the  Nortli  Fork,  platinum  has  been  found  in  a  very  small  amount 
at  two  properties.  One  of  these  is  the  Peterson  mine  in  Eddy's  Gulch 
about  three  miles  from  Sawyers  Bar.  There  is  a  slate  bedrock  here, 
striking  northeast  and  diping  40°  SE.  This  gulch  is  wide  and 
U-shaped,  in  striking  contrast  to  the  other  stream  caiions  of  the  district. 
The  material  filling  it  is  mostly  rough  and  angular.  There  is  a  bank 
60  feet  thick,  of  wliich  25  feet  is  apparently  pay  gravel.  There  is  a 
high  percentage  of  rocks,  and  black  sand  is  almost  entirely  absent,  in 
contrast  wit"h  the  high  percentage  found  in  the  river.  While  no  time 
was  taken  to  verify  the  supposition,  it  is  thought  that  Eddy's  Gulch  is 
undoubtedly  an  old  glacial  trough,  although  some  of  the  material  now 
filling  it  probably  came  from  landslides.  The  gold  found  here  is  rusty, 
rough  and  coarse,  often  with  quartz  attached.  The  few  pieces  of 
platinum  saved  are  rough  and  covered  with  a  black  and  rusty  coating. 
This  material  shows  few  signs  of  erosion.  The  largest  nugget  weighed 
23  grains.  The  nuggets  have  flat,  angular  shapes  and  are  probably 
osmiridium.  Eddy's  Gulch  has  produced  a  great  deal  of  placer  gold, 
and  is  still  yielding  well,  although  Peterson  is  the  chief  operator  and  he 
mines  only  about  5000  yards  annually.  Several  productive  cpiartz 
mines  were  formerly  operated  in  its  upper  branches  where  the  spacious 
U-shaped  canon  is  very  pronounced.  Evidently  no  small  stream  like 
the  present  one  could  have  done  such  work.  The  only  outcrop  of  ser- 
pentine visible  in  this  trench  is  a  small  body  lying  at  an  elevation  of 
3500  feet  on  the  trail  to  Black  Bear  Summit. 

The  only  other  producer  of  platinum  on  the  North  Fork  was  the 
bench  mine  at  the  mouth  of  Jessop's  Gulch.  William  Wike  and  a 
partner  took  a  contract  here  many  years  ago  to  clean  the  bedrock  after 
hydraulicking  was  suspended.  They  made  $6  a  day  each  in  gold  for 
nearly  a  year,  but  their  saving  of  platinum  metals  amounted  to  only 
about  I  ounce  in  all.  This  was  loaned  to  the  writer.  The  largest  piece 
weighs  _-  grains.     This  nugget  shows  a  rounded  surface  but  most  of 


PLATINUM    AND    AIXIED   METALS. 


81 


82  CALIFORNIA    STATE   MINING   BUREAU. 

the  metal  is  in  irregular  unworn  nnggets  and  in  jagged  scales  exhibiting 
perfect  basal  cleavage  faces,  indicating  osmiridimn.  Boiling  in  con- 
centrated acid  readily  removed  the  black  coating  and  accentuated  the 
sharp,  unworn  cliaracter  of  the  material.     (See  Plate  I.)     * 

JUNCTION  CITY  DISTRICT. 

This  is  usually  the  first  region  tliought  of  when  platinum  production 
in  California  is  mentioned.  The  distinction  is  due  to  the  occurrence  of 
numerous  nuggets  of  mixed  platinum  metals  which  have  been  saved 
here.  These  nuggets  are  th(^  largest  of  the  kind  ever  found  in  the 
state.*  The  district,  which  is  confined  to  Trinity  River  and  the  lower 
(ourses  of  its  tributaries,  is  bounded  upstream  by  the  mouth  of  Dutch 
Creek  and  the  downstream  limit  is  placed  at  North  Fork  or  Helena,  for 
the  purposes  of  this  report,  because  there  is  such  a  small  production 
find  so  little  mining  activity  between  there  and  the  South  Fork. 

An  automobile  road  runs  from  Weaverville  to  North  Fork  via 
Junction  City,  and  from  the  latter  place  a  road  crosses  the  river  and 
runs  as  far  as  Dutch  Creek.  The  numerous  perennial  streams  have  cut 
deep  caiions  in  reaching  the  river,  which  in  turn  has  left  a  number  of 
terraces  carved  on  the  canon  side  to  mark  its  earlier  Quaternary 
channels.  At  present,  the  river  is  overloaded  with  sand  and  gravel 
tailings  of  the  La  Grange  hydraulic  mine.  Most  of  the  hydraulic 
ground  in  the  district  is  exhausted  and  a  good  part  of  that  remaining 
can  not  be  worked  until  water  is  supplied.  There  is  one  dredger  below 
Junction  dity  which  produces  nearly  all  the  platinum  saved  in  the 
region. 

Geology. 

No  S3^steraatic  study  has  been  made  of  the  geology  of  this  immediate 
district,  and  such  study  was  outside  the  province  of  the  present  paper. 
The  rocks  of  the  region  have  been  roughly  grouped  under  two  heads  by 
J.  P.  Smith  on  his  Geological  Map  of  California,  published  by  the  Cali- 
fornia State  Mining  Bureau.     The  older  series,  or  'Pre-Cambrian  Meta- 
:  inorphics, '  is  one  in  which  gneiss,  hornblende  schist  and  mica-schist  are 
-the  dominant  rocks.     This  series  lies  mostly  east  of  the  river,  but  the 
contact  is  badly  warped  and  crosses  the  stream  several  times.     The 
^younger  rocks  lie  principally  west  of  the  river.     Smith  groups  them 
'under   the   title    of   Paleozoic    Metamorphics,   Undifferentiated.     This 
■classification  is  useful  to  contain  all  the  rocks  of  sedimentary  origin, 
•including  shaly  cherts  and  limestones,  the  age  of  wdiich  has  not  bee 
determined  because  of  a  paucity  of  fossils;  here  also  are  grouped  th 


*The  Placerville  Republican  of  January  29,  1917,  reported  that  a  nugget  of  plati- 
num valued  at  $105  had  recently  been  recovered  one-half  mile  from  Fairplay,  a  small 
.camp  near  the  Middle  Fork  of  Cosumnes  River,  in  El  Dorado  County.  There  is  no 
other  record  of  platinum  nuggets  being  recovered  from  that  region. 


II 


I 


PLATINUM   AND   ALLIED   METALS,  83 


many  areas  of  serpentine  found  in  association  with  the  chert  and 
various  rocks  of  igneous  origin  which  have  undergone  the  ddoritic  or 
'greenstone'  form  of  alteration. 

The  older  series  is  exposed  typically  on  the  southwest  slope  of 
Weaver  Bally.  Here  hornblende  schist  sliows  evidence  of  much  folding 
and  crumpling,  having  been  compressed  by  contraction  along  a 
rorth west-southeast  line.  This  compression  is  shown  in  its  larger 
aspects  in  the  La  Grange  fault  about  five  miles  south  where  Tertiary 
j^ravels  lie  thrust  upon  a  rim  of  schist,  with  slate  to  the  south.  Schist- 
osity  along  a  northeast  direction  is  plainly  developed  in  this  formation 
where  it  appears  along  the  river  in  the  bedrock  of  the  hydraulic  mines. 
jMica  schist  is  prominent  west  of  the  river  near  Dutch  Creek  and 
actinolite  schist  in  the  bedrock  of  mines  near  Mill  Creek. 

The  chert  and  limestone  of  the  younger  series  have  been  crushed  so 
that  the  chert  is  badly  broken  up  and  the  limestone  largely  changed  to 
gray  marble,  but  the  original  strike  of  the  beds  to  the  northwest  is 
usually  traceable.  It  is  evident  this  series  has  escaped  much  of  the 
metamorphism  felt  by  the  older  schists.  The  rather  extensive  beds  of 
limestone  suggest  a  Devonian  deposit.  Serpentine  areas  are  in  general 
enclosed  by  chert  which  is  interlaminated  with  thin  partings  of  shale. 
There  are  some  small  outcrops  of  shale  a  few  feet  in  width. 

Granodiorite  makes  up  the  higher  portion  of  Weaver  Bally.  Younger 
igneous  formations  ranging  in  character  from  very  acid  to  basic,  are  of 
frequent  occurrence  in  dikes. 

The  bench  gravel  deposits  which  have  yielded  the  gold  and  the 
nuggets  of  platinum,  are  derived  from  the  erosion  of  older  gravels,  but 
the  origin  of  these  is  a  mooted  question.  It  seems  simple  enough  to 
trace  them  upstream  to  the  Minersville  district,  but  the  problem  is  com- 
plicated by  a  survey  of  the  field.  The  gravel  on  the  benches  in  the 
district  bounded  upstream  by  the  mouth  of  Dutch  Creek  is  without 
doubt  different  in  origin  from  the  gravel  farther  upstream  on  the  river. 
The  wash  between  Dutch  Creek  and  the  Jacobs  mine  is  characterized  by 
enormous  boulders  which  have  evidently  not  come  dowTistream,  as  they 
are  not  seen  above  Dutch  Creek.  Neither  is  platinum  noted  in  the 
La  Grange  mine,  although  there  are  numerous  boulders  of  large  size  in 
the  gravel  there.  The  disappearance  of  heavy  wash  and  platinum 
nuggets  above  Dutch  Creek  is  coincident,  suggesting  their  common 
origin.  This  origin  may  be  in  the  immediate  vicinity;  the  l)oulders 
may  represent  fault  breccia,  landslide  material,  or  glacial  debris 
brought  from  the  northeast,  from  the  region  of  the  Sawtooth  IMountains. 
Insufficient  study  of  the  geology  has  been  made  to  defend  or  disprove 
either  hypothesis. 


84  CALIFORNIA   STATE    MINING   BUREAU. 

Production  of  Platinum. 

Chief  among  the  producers  of  platinum  here  is  the  Valdor  dredge. 
This  is  working  on  the  Trinity  River  about  five  miles  below  Junction 
City,  on  what  was  formerly  known  as  the  Hertevant  mine.  The 
machinery  of  fhe  dredge  is  principally  of  Union  Iron  Works  manufac- 
ture and  the  hull  is  built  from  timber  sawed  on  the  company's  land 
nearby.  The  bucket  line  carries  69  buckets  of  7  cubic  foot  capacity. 
The  boat  can  handle  5000  cubic  yards  a  day.  It  is  100  feet  long  and 
carries  about  1550  square  feet  of  gold  saving  tables.  Electric  power  is 
bought  from  a  company  which  has  a  generating  plant  just  below  Junc- 
tion City.  Cost  per  yard  to  work  this  ground  is  only  a  fraction  of  a 
cent  higher  than  at  Oroville.  but  of  course  the  cost  of  bringing  in 
machinery  from  Redding,  about  65  miles  distant  over  steep  roads,  was 
heavy.  The  dredge  is  at  an  elevation  of  1424  feet  and  in  August,  1917, 
was  working  on  the  north  bank  of  the  Trinity,  although  the  possibility 
of  crassing  the  river  was  being  considered.  Dredging  began  here 
November  18.  1916.  Up  to  July  1,  1917.  about  900,000  cubic  yards  had 
been  dredged. 

The  ground  consists  of  river  gravels  and  alluvium  which  has  been 
laid  down  in  one  of  the  few  places  where  the  canon  widens  out.  When 
visited,  only  74  acres  had  been  proven  as  dredging  ground,  but  there  is 
no  doubt  a  considerable  area  in  the  region  upstream  and  across  the 
river.  The  ground  was  worked  by  surface  and  drift  mining  from  the 
'50 's  onward  and  on  the  oppo.site  bank  a  great  deal  of  hydraulic  mining 
has  been  carried  on  all  the  way  upstream  to  the  mouth  of  Dutch  Creek. 
All  these  hydraulic  properties  were  rich  in  gold  and  produced  con- 
siderable platinum,  so  that  it  was  reasonable  to  look  for  rich  ground 
here.  The  average  depth  to  bedrock  is  24  feet  with  extremes  of  15^ 
and  33  feet,  but  the  bedrock  often  contains  deep  holes  which  the  bucket 
can  not  clean.  Every  hole  drilled  showed  either  serpentine  or  limestom 
bedrock.  The  actual  results  obtained  by  dredging  in  many  cases  wer( 
exactly  opposite  to  drill  indications.  Ground  which  drilled  as  high  a 
40^  a  yard  was  dredged  at  a  loss  of  several  cents  a  yard,  and  some 
ground  which  prospected  2(^  or  2>f  a  yard  proved  very  rich.  A  typical 
section  in  a  hole  33  feet  deep  sliows  (1)  12  feet  of  soil;  (2)  9  feet  loos^ 
fine  gravel;  (3)  6  feet  hard  coarse  gravel;  (4)  2  feet  loose  gravel 
(5)  3  feet  medium  loose  coarse  gravel.  The  gold  is  found  on  and  withi 
three  feet  of  bedrock.  Usually  a  foot  or  more  of  bedrock  is  dug. 
Nearly  all  the  gold  is  saved  on  the  first  two  tables,  but  there  are  few 
nuggets  found. 

More  careful  and  systematic  work  in  saving  platinum  has  bee 
carried  on  here  than  anywhere  in  the  northwestern  counties.  Tb 
location  of  the  property,  only  about  nine  miles  downstream  from  th 
celebrated  Chapman  mine,  and  nearer  to  other  hydraulic  mines  where 


r 


PLATINUM    AND   ALLIED    METALS.  85 


1  platinum  nuggets  were  fonnd,  also  makes  the  property  of  special 
interest.  Platinum  metals  occur  as  fine  flakes  and  as  crystalline,  sharp 
edged  pieces.  The  former,  no  doubt,  are  platinum,  the  latter  osmir- 
idium.  Over  a  period  of  several  months,  the  ratio  of  platinum  metals 
to  gold  (by  value)  averaged  about  1|:100.  This  gravel  yields  from 
five  to  six  times  as  much  platinum  metals  per  yard  as  the  dredging 
ground  on  the  Yuba,  Feather  or  American  rivers. 

I  The  platinum  is  recovered  principally  by  hand  panning  of  the  long- 
jtom  concentrates.  A  small  part  is  saved  with  the  hard  amalgam.  TTie 
black  sand  from  the  dredger  is  brought  to  the  clean-up  house.  To 
reduce  the  bulk  it  is  run  through  a  long  torn  several  times.  This  long 
itom  is  11  feet  in  length  and  1  foot  wide  and  is  made  of  2  inch  lumber. 
Jt  has  a  grade  of  1^"  to  a  foot,  and  the  bottom  is  covered  with  riffles. 
I  The  dredger  product  enters  through  a  hopper  which  screens  out  coarse 
pebbles  and  base  metal  over  ^  inch.  Hard  amalgam  with  a  little 
platinum  is  first  recovered.  Continued  panning  of  the  sand  saved  in 
ithe  long  tom  gives  in  the  following  order:  ^Mercury  and  soft  amalgam; 
jbase  metal  carrying  some  amalgam,  which  is  saved  in  a  base  bar;  free 
iplatinum  concentrate,  carrying  about  90%  platinum  metals;  and  No.  1 
black  sand  concentrate.  The  main  body  of  sand  is  saved  and  the  coarse 
material  over  Y^  is  examined,  although  nuggets  of  gold  are  rare,  the 
largest  found  in  nine  months  weighing  about  ^  ounce.  No  platinum 
larger  than  a  wheat  grain  has  been  found. 

Various  tests  have  been  made  on  the  black  sand  concentrate  after 
]  .inning  out  as  much  as  possible  of  the  gold  and  platinum.  Tabling 
tests  indicated  that  one  ton  of  the  sand  carries  .112  oz.  gold,  .016  oz. 
platinum,  and  .014  oz.  osmiridium.  Only  five  tons  of  such  sand  were 
accumulated,  however,  in  dredging  nearly  1,000,000  cubic  yards,  so 
[that  the  loss  is  not  serious  if  these  tests  are  correct.  Screen  tests  of 
the  residual  black  sand  showed  that  93%  of  the  gold  and  all  the 
platinum  remaining  in  it  is  finer  than  10  mesh.  Assays"  vary  consid- 
erably. The  last  one  furnished  the  writer  showed  43.2%  platinum, 
47.5%  osmiridium  and  1.3%  gold,  leaving  8%  of  the  'crude  platinum' 
without  value.  Another  lot  of  over  nine  ounces  carried  30.5%  plati- 
num, 54.2%  osmiridium  and  1.72%  gold.  The  gold  also  varies  greatly 
in  fineness,  running  from  $16.15  to  $18.76  an  ounce. 

!  LOWER  SOUTH  FORK  AND  MAIN  TRINITY  RIVER. 

! 

,  This  area  includes  the  main  river  from  the  end  of  the  canon  near  the 
mouth  of  New  River  to  Willow  Creek,  and  the  South  Fork  of  Trinity 
'from  Big  Oak  Flat  to  the  mouth,  with  the  gravel  which  has  been 
(h'posited  on  the  series  of  benches  between  the  two  streams. 


86  CALIFORNIA   STATE   MINING   BUREAU. 

The  mines  here  are  located  on  terrace  gravels  which  have  been  opened 
in  different  properties  from  near  the  level  of  the  river  to  an  elevation  of 
840  feet  above  it.  A  careful  study  of  this  region  ought  to  shed  much 
light  on  the  history  of  the  Trinity  Caiion.  The  series  of  ])enches 
appears  to  be  preserved  better  in  the  small  area  around  the  mouth  of 
the  South  Fork  than  anywhere  else  on  the  Trinity  River.  There  is  a 
striking  similarity  between  this  series  of  terraces  and  the  series  studied 
by  Hershey^  at  Orleans,  Humboldt  County.  However,  Hershey  stated 
that  the  highest  bench  at  Orleans  is  850  feet  above  the  present  Klamath 
River.  The  highest  terrace  noted  at  the  place  mentioned  on  the  Trinity 
is  about  1000  feet  above  the  river.  Considering  that  the  two  terrace 
systems  represent  probably  the  same  time  period  it  is  evident  that 
Trinity  River  has  maintained  a  uniformly  faster  rate  of  caiion  cutting 
in  Quaternary  times  than  the  Klamath,  due  to  differences  in  stre.im 
grades,  and  in  directions  of  flow  with  respect  to  the  strike  of  underlying 
formations. 

The  complete  set  of  gravel-covered  benches  appear  on  the  Hammer 
property,   sometimes  known  as  the   South  Fork  Gold  and  Platinum 
Mining  Company,  of  which  P.  P.  Hammer  of  Willow  Creek  is  principal 
owner.     These  holdings  comprise   885  acres  lying  between  the  main 
Trinity  and  its  south  fork,  with  a  length  of  J  mile  up  the  main  stream. 
The  highest  or  sixth  bench,  1000  feet  above  the  river,  is  unprospeeted, 
but  there  is  probably  ^  mile  of  it  here.     The  fifth  bench  is  841  feet 
above  the  water  and  has  been  traced  for  about  one  mile.     It  has  been 
mined  a  little ;  about  I  acre  has  been  hydraulicked  by  Mr.  Hammer  and 
has  proven  to  be  good  ground.     The  fourth  bench  has  not  been  workec 
or  thoroughl}^  prospected.     Its  edges  show  occasionally  as  a  bare  rod 
platform  on  the  road  up  the  South  Fork.     The  third  bench  has  beei 
extensivel}^  prospected  and  has  been  mined  on  the  Hammer  property 
and  on  the  adjoining  properties  lying  on  the  east  bank  of  the  Soutl 
Fofk.     This  channel  has  a  length  of  f  mile  and  has  proven  to  be  pro-' 
ductive  ground.     The  gravel  is  47  to  50  feet  deep  with  no  overburdenj 
The  floor  of  this  bench  is  about  450  feet   (aneroid)   above  the  river.] 
The  bench  is  prominently  developed  clear  across  the  area  between  the 
two  branches  of  the  river.     The  second  bench  has  been  tested  by  shafts 
and  tunnels  and  found  to  carry  from  8^  to  20^5  a  cubic  yard.     This 
bench  passes  under  the  house  of  an  adjoining  landowner,  who  contested^ 
the  mineral  character  of  the  land.     The  suit  brought   out  evidence 
showing  that  the  entire  Hammer  holdings  are  mineral  land.     Some' 
samples  from  the  second  bench  went  as  high  as  $3  a  cubic  yard.     This 
bench  has  been  mined  in  a  small  way  on  the  opposite  side  of  the  riverj 
from  the  Martin  house,  and  yielded  satisfactorily.     The  first,  or  lowest] 


^Hershey,  O.  H. :  River  Terraces  of  the  Orleans  Basin,  California.     Bulletin  of  Dept.l 
Of  Geology,  Univ.  of  Cal.,  Vol.  3,  No.  22. 


PLATINUM    AND   ALLIED    METALS.  87 

bench,  has  not  been  mined  on  this  property,  but  higher  upstream  has 
been  proven  productive.  Tliis  bench  is  well  developed  around  the 
mouth  of  the  South  Fork,  where  the  present  stream  flows  in  a  steep 
canon  cut  in  the  roclis  to  a  depth  of  60  to  70  feet  below  the  first  bench. 
These  six  terraces  are  thought  to  represent  the  entire  series  of  stages 
of  the  downcutting  Quaternary  Trinity  River.  Not  all  of  them,  prob- 
ably, occur  so  conveniently  situated  for  observation  anywhere  else  on 
the  river,  although  as  many  as  three  or  four  can  be  seen  at  places  like 
Junction  City. 

As  little  known  as  these  bench  gravels  are,  they  have  been  mined 
enough  to  indicate  that  they  are  probably  richer  in  platinum  than  any 
other  known  area  of  mining  ground  in  the  state.  The  platinum  on  the 
Hammer  ground  is  coarser  than  would  be  expected  so  far  downstream, 
and  evidently  contains  a  large  proportion  of  osmiridium.  As  noted 
above,  Hammer  is  operating  two  small  hydraulic  mines  on  his  holdings. 
One  is  on  the  fifth  bench,  where  Dutchman's  Gulch  cuts  through  the 
gravel.  One-fourth  acre  of  ground  has  been  mined  here,  which  Ham- 
mer says  has  yielded  $6,000,  and  has  given  as  much  as  four  ounces  of 
platinum  for  $1,000  in  gold.  In  one  50-hour  run  with  a  6-inch  pipe 
and  3-inch  nozzle,  nearly  one  ounce  of  platinum  was  saved.  The  gold 
is  flat,  ranging  around  the  size  of  wheat.  Platinum  flakes  the  size  of 
two  pinheads  are  common,  and  both  gold  and  platinum  are  clean  and 
bright.  Nearly  15  ounces  of  platinum  are  said  to  have  been  produced 
from  this  ground.  The  very  high  proportion  of  the  platinum  to  the 
gold  can  be  realized  when  it  is  remembered  that  15  ounces  represent 
ihe  average  yearly  production  of  platinum  from  two  California  dredgers 
handling  from  200,000  to  240,000  cubic  yards  a  month. 

On  the  South  Fork,  possibly  a  mile  upstream  from  the  mouth. 
Hammer  has  opened  a  mine  in  the  gravel  of  the  tlii  rd  bench  and  has 
found  ground  which  has  yielded  well.  The  bedrock  is  slate.  Where 
now  working,  the  gravel  is  30  feet  deep,  but  increases  to  47  feet  nearby. 
There  are  two  strata  of  gravel  in  the  bank,  colored  red  and  blue;  the 
latter  is  the  richer,  and  has  shown  a  value  of  37^  a  cubic  yard  as  against 
18^  for  the  red  phase,  where  they  were  prospected  by  shaft.  The 
recovery  from  the  ground  actually  mined  has  exceeded  these  prospects 
as  Mr.  Hammer  claims  to  have  realized  over  60^  a  yard.  The  gold  is 
m  flakes  of  medium  size,  seldom  smaller  than  No.  2.  Platinum  colors 
can  be  easily  panned  on  the  bedrock.  They  range  from  very  fine  to 
No.  2  size.  The  amount  of  gi'ound  moved  here  has  been  small,  because 
very  little  water  is  available. 

These  Hammer  holdings  no  doubt  contain  as  good  grade  of  gravel 
as  remains  unworked  in  California.  Failure  to  work  them  on  a  larger 
scale  has  been  due  to  lack  of  water,  and  adverse  claims  of  agriculturists 


88  CALIFORNIA    STATE   MINING   BUREAU. 

who  for  many  years  have  contested  the  character  of  the  land.  The 
problem  of  water  supply  has  been  the  chief  difficulty.  There  are  no 
streams  nearby  high  enough  to  put  water  on  the  fifth  bench.  The  only 
water  now  available  there  is  the  run-off  during  the  winter  rains.  Two 
miles  of  ditches  have  been  dug  to  encircle  the  hill  80  feet  above  this 
bench,  and  these  ditches  serve  as  reservoirs  which  permit  washing  with 
one  giant  during  wet  weather.  It  is  estimated  that  a  water  supply 
sufficient  for  six  months  steady  piping  anywhere  on  the  885  acres  could 
be  obtained  from  Eltapom  Creek,  a  branch  of  the  Hayfork,  by  building 
18  miles  of  'ditch  and  flume.  For  a  full  year's  supply,  it  is  thought 
that  it  would  be  nece.ssary  to  tap  the  Hayfork  at  a  distance  of  34  miles. 
A  siphon  from  Campbell  Creek  would  furnish  a  supply  for  the  third 
bench  gravel.  This  compares  favora])ly  with  the  La  (Jrange  property, 
where  it  was  found  necessary  to  go  29  miles  for  a  water  supjiiy,  and 
where  the  gravel  has  never  approached  in  richness  the  prospects 
reported  on  the  above  property.  The  gravel  is  loose  and  easily  worked 
and  there  is  ample  grade  with  plenty  of  space  for  dump. 

An  interesting  prospect  was  opened  in  the  gravel  of  the  third  bench 
on  the  Keen  Ranch,  on  the  South  Fork  about  one  mile  above 
Hammer's  property.  There  are  possibly  50  to  60  acres  of  gravel  here, 
averaging  25  feet  deep.  The  bedrock  is  slate  and  the  gravel  is  medium 
to  fine,  Avith  a  blue  color  throughout.  One  winter  Mr.  J.  A.  Koon,  the 
owner,  hydraulicked  a  little  of  this  gravel,  handling  in  all  about  2200 
cubic  yards.  The  gold  recovered  amounted  to  $150,  and  Koon  estimates 
that  he  also  cleaned  up  between  three  and  four  ounces  of  platinum. 
Unfortunately,  he  was  unacquainted  with  this  metal  and  discarded 
all  of  it  except  1^  ounces  which  he  noAv  has  on  hand.  There  is  no 
reason  to  doubt  the  accuracy  of  JNIr.  Koon's  statement.  This  was  a 
remarkable  yield,  and  strongly  corroborates  the  figures  of  platinum  yield 
and  the  writer's  observations  at  other  properties  nearby.  The  gold  and 
platinum  in  this  gravel  are  fine  and  flaky. 

Continuing  up  the  South  Fork,  we  reach  a  considerable  bend  in  the 
river  at  Sec.  26,  T.  6  N.  The  bend  surrounds,  on  three  sides,  an  area 
of  about  100  acres  of  high  gravel,  known  as  Big  Oak  Flat.  This  is 
considered  by  those  most  familiar  with  the  region,  to  be  the  limit  of  the 
Main  Trinity  River  wash,  as  distinguished  from  South  Fork  material. 
At  any  rate  it  appears  to  be  the  limit  of  pay  gravel  as  we  ascend  the 
stream.  A  number  of  years  ago,  this  flat  was  quite  thoroughly  pros- 
pected by  shafts  and  tunnels.  The  average  value  was  determined  to 
be  6^  a  cubic  yard,  according  to  the  man  who  had  charge  of  the  pros- 
pecting. The  idea  of  hydraulicking  it  was  consequently  abandoned. 
An  unsubstantiated  report  was  made  at  one  time  that  platinum  occurs 
on  the  Carpenter  property.  Sec.  12,  T.  5  N.,  R.  5  E.,  in  the  ratio  of 


PLATINUM    AND   ALLIED   METALS.  89 

4  or  5  parts  to  one  of  gold,  ])nt  it  is  believed  that  the  gold  content  there 
is  too  low  for  mining  profitably. 

Little  is  known  abont  the  gravel  which  may  lie  on  the  west  side  of 
the  South  Fork.  No  claims  have  been  located  there  yet,  althongli  a  face 
of  gravel  has  been  noted  several  hundred  feet  al)ove  the  stream. 

On  the  main  Trinity  between  the  months  of  South  Fork  and  Xrw 
River  there  are  several  hydraulic  properties  which  for  the  most  part 
have  been  operated  for  a  short  season  during  the  winter.  There  has 
been  considerable  friction  here  l)etween  miners  and  agriculturalists  and 
land  probably  more  valual)l('  potentially  for  mining  tlian  for  farming 
is  being  held  in  some  cases  by  homestead ing. 

(This  district  was  covered  by  H.  G.  Ferguson  of  the  U.  S.  Geol. 
Survey  but  the  following  notes  obtained  by  the  writer  are  given  here 
because  they  may  contain  some  items  of  information  in  addition  to  that 
obtained  by  Ferguson.) 

Gem  Placer,  Teal  and  Ferigot,  owners,  has  yielded  possibly  20 
ounces  of  platinum.  There  are  400  acres  in  these  holdings.  Season 
averages  six  months.     Platinum  to  gold  ratio  of  one  to  ten  by  (|uantity. 

Top  Notch  Mine,  F.  Ranney,  owner.  This  property  was  mentionetl 
in  a  former  report^  as  producing  platinum  in  the  ratio  of  one  ounce 
to  six  ounces  gold.  Ranney  states  this  figure  is  too  high;  some  of  the 
lowest  and  richest  ground  made  a  small  yield  at  rate  of  one  ounce 
platinum  to  ten  of  gold.     The  mine  is  not  being  worked  now. 

Hawkins  Bar,  Jerry  Smith,  owner.  Located  in  Sees.  28.  29,  T.  6  X.. 
R.  6  E.,  and  contains  340  acres.  This  property  is  ecpiipped  for 
mining  and  has  made  some  production  in  the  past,  both  of  gold  and 
platinum.     It  is  not  now  being  worked. 

The  Henderson  Mine,  in  Sec.  18,  T.  6  N.,  R.  5  E.,  contains  GO  acres 
and  is  equipped  for  hydraulicking.  It  is  a  small  producer  of  gold  and 
platinum. 

All  these  properties  are  able  to  make  only  a  short  season's  run  on 
account  of  water  scarcity. 

The  Corona  de  Ore  Mine  is  located  on  the  Trinity  River  in  Sees.  17 
and  20,  T.  6  N.,  R.  6  E.,  six  and  one-half  miles  from  the  mouth  of  the 
South  Fork.  There  are  several  benches  of  gravel  on  this  property,  the 
highest  of  which  is  about  800  feet  above  the  river  and  probably  coi-- 
responds  to  the  fifth  bench  on  tlie  Hammer  property.  The  gravel  has 
been  opened  in  one  of  the  lower  benches  with  satisfactory  returns  in 
gold  and  platinum,  but  troubles  among  the  stockholders  and  (liflicnlly 
in  applying  proper  mining  metliods  liavc  retarded  progress. 


'Cal.  state  Min.  Bur.,  Mines  and  Mineral  Resources  of  Trinity  County,  1915. 


90  CALIFORNIA    STATE   MINING   BUREAU. 

Six  hundred  fifty  inches  of  water  is  taken  from  Cedar  Creek,  a  brancli 
of  Horse  Linto  Creek,  through  10  miles  of  ditch  and  tunnel,  and  a  five- 
inch  giant  working  wath  260  feet  head  is  used  in  hydraulicking.  Use 
of  large  quantities  of  water  and  the  attempt  to  put  through  a  big  yard- 
age are  thought  by  some  of  the  stockholders  to  have  resulted  in  loss  of 
considerable  fine  gold  and  platinum,  but  nevertheless  the  reported 
recovery  has  been  at  the  rate  of  28^  a  cubic  yard  in  gold.  At  the  cur- 
rent rate  paid  for  Trinity'  Eiver  platinum  metals,  there  has  been  a 
yield  of  4.6^  a  yard  for  the  platinum  saved,  making  a  total  of  nearly 
33^  a  yard.  With  more  careful  manipulation  and  the  installation  of 
an  undercurrent,  it  ought  to  be  possible  to  increase  largely  the  recovery 
of  both  fine  gold  and  platinum.  The  largest  gold  nugget  so  far  found 
was  worth  ,$5.00,  and  the  platinum  is  said  to  be  all  fine.  The  gravel 
is  medium  and  easy  to  work.  It  contains  a  large  amount  of  pyrite, 
probably  derived  from  the  erosion  of  the  slate  which  is  the  commonest 
bedrock  material  in  that  district.  The  longest  continuous  run  yet  made 
was  12  days.  This  property  ought  to  be  capable  of  producing  15  to  20 
ounces  of  platinum  each  season  if  the  proportion  indicated  by  past 
recoveries  can  be  maintained,  and  if  mining  can  be  kept  up  for  three  to 
four  months  each  season.  The  width  of  the  gravel  has  not  been  deter- 
mined. Tunnels  200  and  125  feet  long  respectivelj'-,  were  entirel.v  in 
gravel.  The  mine  is  owned  by  the  Corona  de  Oro  ]\Iining  Company, 
Eureka,  California. 

HAYFORK  OF  TRINITY  RIVER. 

Hayfork  Creek  or  the  Hayfork  of  Trinity,  as  it  is  frequently  termed, 
has  a  uniformly  broad,  well-graded  valley.  It  has  two  forks,  the  larger 
of  which  heads  near  the  upper  waters  of  the  South  Fork  of  Trinity 
and  of  Beegum  Creek  and  is  separated  from  those  streams  by  a  moun- 
tain divide  of  about  5000  feet,  which  is  largely  serpentine,  forming  as 
it  does  the  widest  portion  of  the  serpentine  zone  which  extends  from 
Tedoc  IMountain  northwest. 

These  three  streams  are  all  notable  as  platinum  producers.  The 
Hayfork,  in  the  region  of  the  town,  has  produced  large  amounts  of  the 
metal.  As  we  go  toward  the  headwaters  of  Hayfork  the  results  appear 
to  be  less  definite.  On  the  East  Fork  of  Hayfork  there  is  at  present 
little  mining  going  on.  There  are  some  small  areas  of  gravel  which 
pan  promisingly  for  platinum,  but  in  the  greater  part  of  the  .stream 
there  is  no  particular  promise  of  platinum  production.  The  Hayfork 
is  today  a  low-grade  stream,  and  the  broad  valley  is  preserved  to  within 
three  or  four  miles  of  the  sources  of  the  two  forks.  Its  south  fork  at 
Wildwood  flows  in  a  broad  trough  filled  with  fine  sediments. 


PLATINUM   AND   ALLIED   METALS.  91 

The  eastern  slope  of  this  valley  leads  over  an  alluvial  surface  of  gentle 
grade  to  the  top  of  the  divide  which  separates  the  Hayfork  from  the 
Cottonwood  Creek  drainage.  There  is  no  outcrop  of  rock  in  place  on 
either  side  of  the  road  till  one  passes  to  the  Cottonwood  side.  On  the 
road  to  Harrison  Gulch,  slate  in  place  occurs  about  one  mile  below 
the  summit  and  is  prominently  shown  on  the  dumps  of  all  the  gold 
.prospects  in  the  neighborhood  of  Harrison  Gulch. 

Wilson  Creek,  a  tributary  of  Hayfork  a  mile  north  of  the  highway, 
cuts  through  the  alluvial  mantle  and  shows  it  to  consist  chiefly  of  green- 
ish clay.  On  the  Geo.  H.  Knight  Ranch,  which  lies  on  the  highway, 
one-half  mile  from  Green's  Wildwood  Hotel,  a  small  branch  flowing 
west  into  Hayfork  has  cut  through  the  clay  to  a  bedrock  wliich  has  the 
appearance  of  highly  weathered  granite  or  granodiorite.  There  is  a 
stratum  of  greenish  clay  some  throe  feet  thick  under  which  a  thin  layer 
of  angular  wash,  containing  considerable  quartz,  lies  directly  on  bed- 
rock. Mr.  Knight  has  put  a  short  sluice  in  this  branch  and  has  cleaned 
a  very  few  square  yards  of  the  bedrock  scooping  out  the  dirt  from 
beneath  the  clay.  The  clean-up  was  interesting,  more  because  of  its 
character  than  its  value.  The  gold  was  heavy  and  round,  and  had 
traveled  a  very  short  distance.  There  was  a  notalile  proportion  of 
platinum  which  was  bright,  angular  and  coarse.  The  clay  is  probably 
a  portion  of  the  deposits  brought  into  the  Hayfork  basin  when  the  latter 
was  a  ponded  stream.^  Three  or  four  colors  of  platinum  can  be 
obtained  in  a  pan  of  this  wash;  but  panning  the  gravel  and  scraping 
bedrock  along  the  Hayfork  here  rarely  or  ever  gives  a  color;  in  fact, 
only  one  color  was  found  in  a  distance  of  several  miles  on  the  main 
stream. 

Ascending  the  Hayfork,  that  stream  begins  to  take  on  a  steeper  grade 
two  miles  south  of  the  highway.  Here  a  lens  of  tightly  cemented  con- 
glomerate seven  feet  thick  lies  on  a  very  hard  basic  igneous  bedrock. 
The  conglomerate  is  apparently  derived  from  the  bedrock.  It  contains 
boulders  up  to  three  feet  in  diameter.  There  is  a  large  body  of  ser- 
pentine just  to  the  west  of  the  creek  here.  Chromite  has  been  mined 
and  shipped  here  recently,  and  there  are  some  small  bodies  of  it  still  in 
evidence.  Large  areas  of  igneous  rock  rich  in  pyroxene  flank  the  Hay- 
fork to  the  east  and  form  steep  rock  strewn  hills  on  that  side.  String- 
bean  Gulch,  a  tributary  of  Hayfork  to  the  east,  flows  throngli  this 
formation  for  about  two  miles.  Another  similar  outpouring  of  basic 
eruptives  of  the  same  character  but  apparently  not  continuous  with 
this  area  extends  from  the  Hayfork  northwest,  being  in  evidence  on 
both  sides  of  the  highway,  and  forming  prominent  hills  across  the 
upper  basins  of  Salt  Creek  and  Hayfork.     This  rock  is  very  slightly 


^U.   S.   Geol.    Survey  Bull.    196. 


92  CALIFORNIA    STATE   MINING   BUREAU. 

serpentinized  as  a  rule.  It  weathers  to  a  reddish  soil  and  on  the 
weathered  surface  has  a  somewhat  darker  shade  than  terra  cotta.  No 
j)latinura  could  be  panned  in  this  section  of  the  stream. 

A  trip  was  taken  from  the  highway  at  Wildwood  to  the  upper  waters 
of  Prospect  Creek,  which  is  a  tributary  of  the  South  Fork  of  Trinity 
River.  Serpentine  is  a  prominent  rock  in  this  region,  forming  the 
bare  ridges  which  separate  the  two  drainages  with  an  elevation  of 
5000  feet.  The  serpentine  appears  in  association  with  cherts  through 
this  area  till  one  reaches  tlie  watershed  of  Prospect  Creek.  Serpentine 
is  also  prominent  between  Dubakella  ^Mountain  and  the  State  Highway 
and  around  the  headwaters  of  many  tributaries  which  empty  into 
Hayfork  farther  downstream.  It  is  thus  seen  that  serpentine  and 
related  basic  rocks  are  the  prevailing  formations  in  the  Hayfork  water- 
shed. There  are.  however,  no  evidences  of  benching  or  gravel  deposits 
on  these  upper  portions  of  the  streams.  The  5000  foot  divide  is  a 
nearly  level  ridge  which  can  be  travelled  for  miles  on  horseback,  as 
the  serpentine  supports  practically  no  timber  or  brush.  There  are  no 
peaks  of  superior  height  in  the  region,  nearer  than  North  YoUa  Balla. 
The  gravel  of  South  Fork  of  Trinity  River  carries  a  very  little  platinum 
in  the  vicinity  of  Prospect  Creek. 

Platinum  occurrence  along  the  Hayfork  and  its  tributaries  is  appa- 
rently limited  to  the  older  stream  gravels  in  the  lower  courses  of  the 
streams,  and  can  not  ])e  traced  to  a  definite  source  in  the  headwaters, 
above  the  level  of  the  gravel  deposits.  Carrier  Gulch  in  Sec.  23,  T.  31 
N.,  R.  11  W.,  is  credited  with  a  large  but  indefinite  production  in  the 
old  days,  but  there  has  evidently  been  no  platinum  recovered  there 
in  recent  years.  Kingsbury  Gulch,  which  empties  into  Hayfork  at 
the  town,  has  been  mined  for  gold  in  both  veins  and  placer  gravels. 
Two  ounces  of  platinum  were  saved  there  in  1916  with  .$1500  in  gold 
from  a  gravel  mine.     The  i)latinum  was  fine  and  flaky. 

Platinum  occurs  on  the  Hayfork  at  the  mouth  of  Little  Creek.  The 
gravel  bed  here  is  from  two  to  four  feet  deep.  It  is  made  up  of  coarse 
wa.sh  mostly  granitic  and  the  bedrock,  also,  is  a  decomposed  granitic 
rock.  Two  or  more  colors  of  platinum  can  be  obtained  from  every 
pan  taken  from  the  bedrock,  upon  which  the  platinum  values  seem  to 
be  concentrated.  Roy  Peterson  has  located  a  claim  here  and  has  done 
a  limited  amount  of  work,  cleaning  bedrock  and  shovelling  into  sluices. 
No  sales  have  been  made  as  far  as  known,  but  a  small  output  is  possible. 

Platinum  occurs  in  a  similar  way  from  the  mouth  of  Jud  Creek  to 
Bear  Creek,  on  the  Beebee  claims.  Beebee  says  the  proportion  of 
platinum  to  gold  is  1  to  6  in  quantity.  The  work  done  so  far  has  not 
shown  the  amount  of  gravel  which  can  be  mined.     Water  can  be  made 


PLATINUM   AND   ALLIED    METALS.  93 

available  In'  a  pipe  line  750  feet  loii^  to  Jiul  ("reek.     Two  elaiiiis  an- 
held  by  location.     Only  a  little  hand  shoveling  ha.s  been  done. 

If  one  is  to  believe  the  stories  of  the  early  days,  there  nnist  have  Ix-cn 
a  heavy  production  of  platinum.  Tlie  metal  at  the  time  was  worth  only 
|2  to  $3  an  ounce  and  few  wanted  to  bu\-  it  at  tliat  price.  The  white 
miners  probably  threw  away  what  they  found  of  it.  Init  the  Chinese 
were  more  frugal.  It  is  said  to  have  been  recovered  at  the  rate  of  six 
or  seven  ounces  for  .$3,000  gold.  The  Chinese  had  a  pigment  in  which 
they  colored  the  platinum  yellow.  It  was  then  dried  arid  mixed  with 
the  gold,  which  was  sold  whenever  possil)le  at  night  to  local  merchants 
in  order  to  avoid  too  close  examination.  Hayfork  gold  thus  came  to 
liave  a  poor  name,  and  could  command  only  about  $16  an  ounce. 

PLATINUM  IN  PLACE. 

]\Iost  of  the  information  available  regarding  platinum  metals  as  con- 
stituents of  viens  in  California  is  hearsay,  not  supported  by  subsequent 
development  or  even  proven  ])y  reliable  assays. 

Shasta   County. 

The  only  well  established  case  is  that  of  platinum  metals  recovered 
in  the  electrolytic  refining  of  blister  copper  from  the  Iron  Mountain 
mine  of  the  Mountain  Copper  Company  in  Shasta  County.  Ledoux  & 
Company  of  New  York  sampled  blister  copper  for  the  above  company  at 
the  eastern  refinery.  They  reported  in  September,  1917,  that  their 
analyses  showed  that  the  blister  copper  carried  platiiuuu  at  the  rate  of 
.001  oz.  per  short  ton. 

Palladium  was  not  recognized  in  50  A.  T.  samples.  This  figure  is 
much  lower  than  the  estimate  quoted^  by  Eilers.  It  is  worth  noting 
that  assays  made  on  copper  ores  from  other  Shasta  County  properties 
have  failed  to  show  the  presence  of  platinum. 

Twenty  years  ago  considerable  excitement  was  caused  in  Harrison 
Gulch.  Shasta  County,  by  the  reported  discovery  of  platinum  in  ore 
from  a  tunnel  near  the  roadside  between  Wildwood  and  Harrison  Gulch 
and  only  a  short  way  below  the  summit  of  the  divide  between  the  two 
counties,  just  within  the  slate  belt.  This  property  was  abandoned  long 
ago,  and  no  definite  information  is  available  about  it  now.  P^xtensive 
work  in  the  slate  belt  at  Harrison  Gulch,  where  millions  in  gold  have 
been  taken  out,  has  not  produced  any  platinum  as  far  as  known,  so  the 
authenticity  of  the  above  find  is  open  to  question.  It  should  be  noted, 
however,  that  platinum  was  panned  by  the  writer  about  three  miles 
from  this  prospect  near  Wildwood,  and  that  it  was  impossible  to  connect 
this  platinum  with  the  extensive  areas  of  basic  igneous  rocks  on  the 
upper  Hayfork  watershed. 


'Trans.   A.  I.   M.   E.,  Vol.   47,   page  217. 


94  CALIJ^ORNIA   STATE   MINING   BUREAU. 

San    Bernardino  County. 

Platinum  in  association  with  lead  carbonate  is  reported^  to  have  been 
found  on  the  150  foot  level  of  the  West  End  mine,  near  Cima,  San 
Bernardino  County.  Some  assays  are  said  to  have  indicated  7.61  oz. 
platinum  and  palladium  in  addition  to  considerable  amounts  of  gold 
and  silver.  The  ore  occurs  at  contact  of  limestone  and  granite. 
Inquiries  addressed  to  thi.s  company  remain  unanswered. 

Del    Norte  County. 

Platinum  in  cliromite  from  Del  Norte  County  wa.s  reported  in  "The 
Mining  and  Scientific  Press"  for  June  30,  1917.  The  ore  came  from 
the  northern  part  of  the  county,  southwest  of  Monumental.  The 
reported  assay  indicated  .04  oz.  platinum  per  ton  of  ehromite  ore. 
When  the  writer  visited  the  district  in  September,  1917,  no  one  would 
claim  responsibility  for  the  report,  and  those  acquainted  with  the  facts 
stated  the  story  was  without  foundation. 

Trinity   County. 

Circumstantial  reports  of  the  discovery  of  platinum  in  veins  in  ser- 
pentine at  the  mouth  of  Bell  Gulch  near  Soldier  Creek  in  the  Junction 
Cit}^  district  of  Trinity  County,  came  to  the  attention  of  the  party 
members  while  in  Weaverville.  Color  was  lent  to  such  reports  by  the 
fact  that  the  largest  nuggets  of  platinum  metals  ever  found  in  Cali- 
fornia came  from  the  bench  gravels  of  Trinity  River  in  this  immediate 
locality.  Accordingly,  the  party,  which  included  L.  M.  Prindle  and 
H.  Ct.  Ferguson  of  the  U.  S.  Geological  Survey,  and  the  writer,  spent 
some  time  in  a  careful  reconnoissance  of  the  district.  A  camp  was 
established  near  tlie  mouth  of  Maple  Creek.  Careful  and  persistent 
work  here  failed  to  indicate  the  presence  of  any  platinum  other  than  a 
few  grains  found  with  placer  gold  in  the  bench  and  stream  gravels. 
The  rock  locally  called  serpentine,  is  in  many  cases  a  highly  altered 
greenstone  which  occurs  as  bedrock  in  many  of  the  hydraulic  mines. 
It  is  schistose  and  often  quite  soft,  being  possibly  best  described  as  an 
amphibolite  equivalent  of  serpentine.  Areas  of  this  rock  and  all  the 
areas  of  serpentine  in  the  vicinity  were  carefully  panned  and  examined 
closely.  Several  days  were  spent  in  panning  the  wash  of  the  numerous 
streams  from  Browns  Creek  to  Connor  Creek.  The  results  of  this  work 
were  entirely  negative.  These  creeks  themselves  have  no  gravel  deposits 
in  their  upper  portions  and  have  never  been  mined  with  success. 

The  gold  and  platinum  in  the  district  are  confined  to  the  deposits  on 
the  terraces  formed  by  the  Trinity  River,  and  had  their  origin  no  doubt 
in  veins  a  long  way  north  of  the  river.     The  nuggets  of  platinum  metals 


'Mining  and  Scientific  Press,  August  25,   1917. 


PLATINUM    AND   ALLIED    METALS.  95 

are  woru  smooth  usually  on  all  sides,  exeept  one,  which  has  evidently 
been  protected.  The  finding?  of  these  nuggets  ha.s  been  so  infrequent 
that  no  definite  knowledge  of  their  original  location  in  the  deposit  is  to 
be  had.  The  fact  that  they  are  sometimes  picked  out  of  crevices  in  the 
bedrock  signifies  nothing. 

I  The  serpentine  areas  in  this  region  usually  carry  very  little  chromite. 
On  the  divide  between  the  upper  Hayfork  and  the  South  Pork  there  is 
notal)ly  more  chromite,  but  no  traces  of  platinum  could  be  found  there. 
Maple  Creek,  in  the  same  district,  has  been  mentioned  as  a  place 
where  platinum  and  gold  associated  in  a  quartz  vein  were  found  lately 
by  the  same  prospector  who  claimed  to  have  found  platinum  previously 
in  Bell  Gulch.  Our  party  carefully  prospected  this  stream  and  its 
branches  over  its  entire  course.  Adjacent  serpentine  areas  were  like- 
wise panned  thoroughly,  but  no  color  of  platinum  was  found  except  in 
bench  gravels  left  by  the  retreating  river  at  a  point  which  no  doubt 
was  once  at  the  junction  of  creek  and  river,  but  is  now  some  distance 
upstream  on  Maple  Creek.  Similarly,  platinum  is  obtained  near  the 
mouth  of  Dutch  Creek  from  gravels  formerly  mined  on  the  high  terraces 
liow  some  distance  up  Dutch  Creek.  The  finding  of  platinum  in  the 
terrace  gravels  near  the  mouths  of  these  streams  has  given  a  certain 
plausibility  to  the  argument  that  the  platinum  originated  in  the  country 
rock  within  the  immediate  basins  of  those  streams.  The  deposition  of 
gold  and  platinum  at  these  places  may  well  be  ascribed  to  slowing  down 
of  the  river  currents  or  to  eddies,  or  curves  in  the  river  channel,  which 
are  known  to  often  be  responsible  for  the  deposition  of  gold  at  certain 
points  along  water  courses.  If  the  platiniferous  rock  has  been  brought 
south  by  glaciers  it  might  also  be  said  that  the  erosion  of  the  morainal 
material  by  streams  would  result  in  concentration  of  gold  and  platinum 
;it  the  mouths  of  the  streams  where  retarding  of  the  current  reduces  its 
power  of  transportation.  Sorting  of  this  alluvial  fan  material  by  the 
river  during  high  water  stages  would  result  in  the  concentration  of 
precious  metals  on  the  bedrock,  especially  in  the  case  of  larger  nuggets. 

San   Luis  Obispo   County. 

Traces  of  platinum  in  peridotite  from  the  Santa  Lucia  IMountains 
near  Santa  INIargarita  in  San  Luis  Obispo  County  are  reported  by 
A.  A.  Wheeler  to  have  been  found  in  analyses  made  by  Baker  and 
Company.  The  western  slopes  of  this  range  are  largely  covered  by 
terpentine  areas  in  which  large  deposits  of  chromite  are  widely  dis- 
tributed. Small  bodies  of  copper  ores  are  also  of  frequent  occurrence.^ 
On  the  east  slope,  near  the  summit  of  the  range,  native  copper  occurs 
in  serpentine  as  fine  wires  and  l)ands.     Some  small  rich  bundles  of 

»Cal    State  Min.    Bur.,  Mines  and  Mineral  Resources  of   San  Luis  Obispo  County, 

1916. 


96  CALIFORNIA    STATE   MINING   BUREAU. 

copper  ore  have  been  encountered  where  assays  indicated  several  dollars . 
a  ton  in  gold  and  silver,  but  no  mention  has  been  made  of  platinum  in 
such    eases,    although    it    may    reasonably    be    expected    in    such    an 
association. 

Platinum  and  gold  occur  in  the  beach  sands  of  the  county,  but  no 
profit  has  ])een  realized  from  the  attempts  to  recover  them.  There  are 
no  minable  gold-bearing  gravels  in  the  Santa  Lucia  serpentine  areas. 

Conflicting  reports  have  been  made  on  the  occurrence  of  platinum 
at  the  La  Plata  claim,  near  the  Liberty  Hill  mine's  debris  dam  on 
Bear  River  in  Nevada  County. 

Small  amounts  of  platinum  may  be  reasonably  looked  for  anywhere 
in  California  where  large  areas  of  serpentine  occur.  This  rock  is 
usually  found  to  be  a  poor  one  for  mineral  deposits.  The  irregularity 
and  lack  of  persistence  of  any  ore  in  serpentine  is  well  known.  It  is 
emphasized  by  the  behavior  of  all  our  Coa.st  Range  deposits  of  chromite, 
and  of  quicksilver  where  the  wall  rocks  are  serpentine.  Gold  deposits 
in  serpentine  are  uniformly  small  and  'pockety,'  and  if  platinum  is 
ever  found  in  place  in  such  serpentine  areas,  we  are  justified  in 
expecting  only  the  snuillest  of  stringer  leads,  elusive  and  discontinuous 
in  character. 

During  the  most  productive  period  of  Trinity,  Siskiyou,  Shasta  and 
Plumas  counties'  hydraulic  and  placer  mines,  there  was  a  yearly 
recovery  of  nearly  200  ounces  of  platinum  metals  at  the  San  Francisco 
Mint  from  the  refining  of  gold  from  those  counties.  Although  the 
recovery  is  much  less  now,  the  amount  is  still  considerable.  Practically 
all  of  this  was  from  placer  gold,  there  being  only  one  or  two  reports 
of  traces  of  platinum  in  gold  from  quartz  mines. 

RECOVERY  OF  PLATINUM  FROM  CONCENTRATE. 
Hydraulic   Mining. 

The  hydraulic  miners  of  most  districts  have  as  a  rule  thrown  away 
platinum  for  years.  Some  of  them  did  this  because  the  price  obtainable 
up  to  a  few  years  ago  was  not  considered  Avorth  the  trouble  necessary 
to  get  the  metal.  Others  did  not  know  platinum  when  they  saw  it,  and 
threw  it  away  with  the  black  sand  after  amalgamating  the  gold.  Today 
the  high  price  and  the  urgent  need  in  this  country  for  every  ounce  that 
can  be  produced,  are  going  to  stimulate  production  as  never  before. 
Those  who  have  saved  platinum  from  the  hydraulic  mines  have  had 
only  small  quantities  to  deal  with  and  have  saved  it  simply  by  panning 
as  much  of  it  as  they  could  out  of  the  black  sand  concentrate  left  after 
the  gold  amalgam  was  saved.  It  is  hard  to  get  either  clean  platinum, 
or  to  remove  all  the  platinum  from  the  sand  by  ordinary  panning. 
Better  results  are  obtained  if  the  concentrate  is  screened  and  each 


1 


PLATINUM   AND   ALLIED   METALS.  97 

screen  size  panned  separately  for  its  platinum  content.  The  platinum 
product  shipped  by  the  hydraulic  miner  is  classed  as  'crude  platinum.' 
In  addition  to  the  native  platinum  group  metals,  it  contains  1%  to  2% 
of  gold  and  considerable  black  sand.  Even  Avith  rather  careful  work, 
from  10%  to  15%  of  the  'crude  platinum'  is  composed  of  impurities 
1  without  value. 

Dredging. 

I  The  long  tom  is  in  universal  use  on  dredgers  to  clean  up.  Sometimes 
I  portion  of  the  platinum  is  directly  recovered  in  the  long  tom  with  the 
main  part  of  the  amalgam,  but  mo.st  of  it  is  in  the  residual  black  sand 
concentrate,  "vvhich  also  contains  amalgam,  rusty  gold,  scrap  iron  and 
lead.  This  concentrate  is  run  down  to  small  volume  usually  in  the 
long  tom.  The  base  metals  are  separated  and  saved.  They  contain 
some  amalgamated  gold  which  is  recovered  b}^  running  the  metal  into  a 
bar  and  shipping  to  buyers,  or  sending  in  the  accumulated  base  metal 
periodically  for  smelting.  The  platinum  is  recovered  by  panning  the 
final  long  tom  concentrate  several  times.  Its  separation  from  the  small 
amount  of  gold  is  easy  because  it  will  not  amalgamate  without  special 
treatment,  but  the  panning  is  slow  and  must  be  carefully  done.  In 
many  cases  the  black  sand  receives  no  further  treatment,  but  is  stored 
so  that  it  is  available  for  the  application  of  any  improved  methods  of 
recovering  the  values  remaining  in  it.  This  outlines  roughly  the  prac- 
tice of  many  dredging  companies,  but  each  of  the  larger  companies  has 
its  special  methods  for  the  treatment  of  the  black  sand  after  the 
recovery  of  the  main  batch  of  hard  amalgam,  and  these  processes  Avill 
be  described. 

Methods  Used  in  Featiier  River  District. 

At  Oroville,  the  Natomas  Consolidated  gold  man  collects  the  black 
sand  concentrate  and  amalgam  in  a  box  on  each  dredger  and  runs  it 
through  a  long  tom  till  it  is  reduced  to  one-half  a  small  water  bucket 
full.  The  long  tom  used  is  one  foot  wide,  twelve  feet  long  and  rests 
on  the  gold  tables  so  that  it  has  a  grade  of  one  inch  to  a  foot.  The 
upper  four  feet  of  the  long  tom  are  covered  with  small  iron  riffles  in 
solid  sections  one  foot  long,  the  cross  riffles  being  an  inch  apart  and 
sloping  back.  Below  these,  the  bottom  of  the  box  is  lined  with  cocoa 
matting  under  expanded  metal.  From  this  long  tom  the  concentrate 
is  taken  to  the  clean-up  room.  The  bulk  of  the  amalgam  is  separated 
easily  and  is  retorted.  The  black  sand  containing  platinum  and  a  little 
amalgam  and  rusty  gold  is  washed  several  times  in  a  miniature  long  tom 
and  the  bulk  is  reduced  to  about  one  pint.  This  contains  the  gold  and 
platinum  group  metals.  Tlie  surplus  quicksilver  is  drawn  off,  and  the 
concentrate  is  subjected  to  a  'boiling'  motion,  which  is  imparted  by 

7—46903 


98  CALIFORNIA   STATE   MINING   BUREAU. 

pouring  it  back  and  fortli  between  two  ordinary  crockery  bowls.  This 
removes  nearly  all  the  black  sand.  Concentrated  nitric  acid  is  applied 
to  remove  any  base  metal  and  to  l)righten  the  rusty  gold  so  that  it  will 
amalgamate.  The  platinum  can  be  finally  cleaned  by  magnet  and 
blower  to  remove  the  remaining  black  sand.  All  the  black  sand  is  saved 
for  future  treatment. 

Some  of  the  clean-up  men  at  Oroville  have  made  use  of  the  Kellogg 
black-sand  machine  to  recover  the  platinum  from  the  long-torn  concen- 
trate. In  principle,  this  device  is  an  inverted  funnel  with  pockets 
around  the  circumference.  The  sand  and  water  are  poured  down  the 
sides  and  the  concentration  i.s  brought  about  by  the  boiling  action  when 
the  mixture  flows  into  the  pockets.  This  gives  a  very  rich  concentrate, 
about  50%  metal.  The  machine  appears  to  be  a  good  saving  device.  A 
recent  clean-up  made  with  it  gave  4f  ounces  platinum.  The  residual 
black  sand  from  the  clean-up  was  treated  chemically  and  was  found  to 
contain  only  90  grains  of  platinum.  This  would  indicate  a  recovery 
of  slightly  over  95%  with  the  appliance. 

A.  H.  Sherwood  of  Oroville  has  for  several  years  used  a  chemical 
method  for  recovering  platinum  on  a  small  scale  from  black  sand  con- 
centrate. Plis  process  consists  of  two  stages:  (1)  putting  the  mercury 
and  platinum  in  condition  to  amalgamate,  and  amalgamating  them ; 
(2)  separating  the  amalgamated  gold  and  platinum.  A  patent  has 
been  granted  him  for  the  second  stage,  but  not  as  yet  for  the  initial 
process.  As  his  rights  have  not  been  clearly  defined,  it  is  not  thought 
advisable  to  fully  describe  the  process.  It  is  a  new  application  of  a 
well-known  law  of  chemical  solutions,  and  appears  to  do  all  that  is 
claimed  for  it,  giving  a  beautifully  clean  platinum  and  a  perfect 
recovery  which  would  be  impossible  by  purely  mechanical  means. 

The  process  has  not  been  perfected  to  the  point  where  it  can  be  usee 
on  a  large  scale,  but  this  is  because  of  the  lack  of  apparatus,  and  no^ 
because  of  any  defect  in  the  method. 

Platinum  in  this  district,  as  well  as  in  the  other  central  California 
dredging  fields,  is  uniformly  fine,  either  as  flakes  or  grains.  It  ii 
probable  that  the  best  results  are  not  obtained  in  the  ordinary  practice 
where  panning  and  the  long  tom  are  used.  The  pan  tubs  used  bj 
Oroville  Dredge,  Ltd.,  gave  up  after  careful  final  cleaning  12.2%  oi| 
the  annual  platinum  yield,  which  had  escaped  during  the  monthlj 
clean-ups.  How  much  more  platinum  remained  after  this  last  pannin| 
is  problematical.  The  dredging  superintendents  generally  are  satisfiec 
with  any  results  which  approximate  the  usual  yield  of  platinum! 
They  reason  that  the  platinum  is  in  such  small  quantitj^  at  best  tha^ 
more  careful  work  is  not  justified. 


PLATINUM   AND   ALLIED    METALS.  99 

Methods   Used   in   the  Yuba    River  District. 

Yuba  Consolidated  Goldfields  has  devoted  consiclLTablc  attention  to 
the  treatment  of  the  black  sand  concentrate  obtained  on  their  dredgers. 
;  Their  investment  in  plant  and  labor  for  this  work  is  justified  when  it 
IS  remembered  that  each  of  their  large  dredgers  gives  three  tons  of  sand 
j  concentrate  a  week  and  a  total  of  60  to  70  tons  of  this  product  is  treated 
'  monthly.  The  sand  handled  is  the  black  sand  from  the  long  toms,  one 
of  which  is  used  on  each  dredger  to  recover  as  much  gold  and  platinum 
as  can  be  gotten  in  a  rich  concentrate  of  small  bulk.  The  handling 
of  this  residual  black  sand  concentrate  does  not  ditTer  materially  from 
the  practice  described  elsewhere  for  other  properties,  l)ut  the  work 
done  in  the  sand  plant  is  ditfereut  from  the  methods  followed  elsewhere. 
The  sand  is  ground  in  batches  for  two  hours  in  a  steel  ball  mill,  with 
a  very  weak  cyanide  solution  to  brighten  the  rusty  gold.  The  slime  is 
then  discharged  into  a  well  from  which  it  is  pumped  into  a  small  set- 
tling tank  and  is  subjected  to  cyanide  treatment  in  a  miniature  plant 
M'hich  is  housed  in  the  same  building.  Leading  from  the  ball  mill  is  a 
string  of  sluices  40  feet  long  and  one  foot  wide,  with  a  grade  of  one  inch 
to  the  foot.  This  offers  the  following  impediments  to  the  escape  of 
precious  metals.  (1)  Mercury  trap;  (2)  two  feet  of  silvered  amalga- 
mating plate;  (3)  three  feet  of  iron  cross-rifMes  such  a.s  are  used  in  long 
toms;  (4)  five  feet  of  cocoa  matting;  (5)  eight  feet  of  wooden  riffles 
loaded  with  mercury;  (6)  balance  of  sluice  covered  by  cocoa  matting 
under  expanded  metal.  After  drawing  off  the  .slime  the  mill  is  nm 
open  and  the  sand  discharges  into  this  sluice.  The  process  gives  about 
$40  a  ton  in  gold  and  platinum.  The  extraction  of  gold  is  said  to  be 
nearly  perfect,  but  assays  of  the  sand  tailing  from  the  sluices  indicate 
SOf'  to  lotj-  a  ton  in  platinum  still  remaining.  In  spite  of  the  good 
recovery,  the  tailing  is  left  v.here  it  can  be  gotten  and  the  employes 
are  constantly  on  the  watch  for  any  possi])le  improvements  in  treating 
it. 

Clean-ups  made  by  the  ^Nfarysville  Dredging  Company  give  much 
finer-sized  platinum  than  that  at  Ilammonton.  After  the  recovery  (jf 
the  hard  amalgam  in  the  long  torn  on  tlie  dredger,  the  l)lai'k  sand  is 
sacked  and  brought  to  the  clean-up  room.  It  is  first  I'uii  through  a 
long  tom  12  feet  long  which  is  fitted  with  iron  riffles.  Mo.st  of  the 
amalgam  is  saved  here.  The  sand  is  tiien  rocked  in  a  common  rocker. 
It  is  next  ground  in  batches  of  about  two  Imckets  for  one-half  hour  in 
a  three-foot  arrastre.  A  little  sulphuric  acid  is  used  to  brighten  the 
rusty  gold,  most  of  which  is  caught  in  the  arrastre.  The  sand  is  finally 
washed  through  a  Colorado  amalgamator,  which  is  said  to  get  the 
remaining  values.  The  concentrate  from  the  long  tom,  rocker  and 
arrastre  is  panned  three  times  to  get  out  the  platinum. 


100  CALIFORNIA    STATE    MINING   BUREAU. 

Methods  Used   in    Natoma   District. 

There  is  a  high  percentage  of  black  and  rusty  gold  here  in  some  of  | 
the  old  terrace  gravels  remote  from  the  present  stream.  The  operating 
company  states  that  most  of  the  platinum  saved  is  caught  in  the  base 
trap  of  the  long  tom  which  is  used  on  the  dredger  to  recover  hard  i 
amalgam  and  base  metals.  It  is  stated  that  the  Neill  jigs  do  not  save 
any  platinum,  although  successful  in  gold  saving.  The  final  recovery 
of  platinum  from  the  sand  is  largely  in  the  Senn  Pan-Motion  Batea. 
A  small  Ilardinge  mill  is  used  to  grind  the  sand.  From  this  mill  it 
passes  onto  an  amalgamated  plate  two  feet  wide  and  ten  feet  long  and 
thence  to  tlie  Senn  machine.  This  is  operated  at  IGO  r.  p.  m.  The 
concentrate  given  is  10%  to  30%  black  sand.  The  gold  is  practically 
all  amalgamated  on  the  Batea  and  the  platinum  is  caught  in  the  bowl  at 
the  center.  This  machine  was  modified  according  to  the  ideas  of  E.  E. 
Strouse,  the  company's  gold  man,  and  the  bowl  is  larger  and  deeper 
than  on  the  stock  machine.  In  finally  separating  the  platinum,  the 
Batea  concentrate  is  screened.  It  is  found  to  be  much  easier  to  get  the 
platinum  from  sand  of  its  own  screen  size,  than  from  sand  of  all  sizes. 
Some  sand  stops  on  a  40-me.sh  screen ;  some  of  the  platinum  and  sand 
grains  are  fine  enough  to  pass  100  mesh.  The  material  entering  the 
Ilardinge  mill  carries  about  $75  a  ton  in  values,  and  the  tailing  from 
the  Senn  Batea  is  said  to  assay  $1  gold  and  $1  platinum.  If  these 
figures  are  correct,  the  process  saves  97%  of  the  precious  metals. 

La  Grange   Method. 

The  Huelsdonk  Submerged  Table  Concentrator  has  been  used  (see 
Photo  No.  10)  successfully  for  four  years  in  recovering  platinum,  gold, 
amalgam  and  mercury  from  black  sand  concentrates  at  the  La  Grange 
dredge.  The  concentrator  works  under  still  water  in  a  box  or  trough 
which  is  16  feet  long,  one  foot  wide  inside,  and  about  one  foot  deep, 
being  made  from  two-inch  planks.  A  small  gas  engine  mounted  on 
the  sluice  furnishes  powder  for  shaking  the  screen  and  the  concentrator, 
and  for  pumping  water.  The  shaking  motion  is  given  by  an  eccentric 
with  ^-inch  travel.  The  screen  moves  on  a  single  bolt  support  on  each 
side,  and  the  power  is  applied  against  .springs.  From  the  screen  the 
sand  and  water  pass  on  to  an  apron  which  extends  one-half  the  length 
of  the  sluice  and  is  perforated  at  regular  intervals  so  as  to  distribute 
the  sand  along  the  table  proper.  This  apron  and  the  table  are  bolted 
together  and  are  shaken  at  the  rate  of  180  r.  p.  m.  They  travel  on 
rollers  along  the  bottom  of  the  sluice,  and  require  little  power.  The 
table  proper  is  essentially  a  long  narrow  galvanized-iron  covered  trough, 
extending  the  full  length  of  box,  and  tapering  at  the  lower  end  to  a 
groove  scarcely  :J-inch  wide  and  deep.  The  sand  enters  the  groove  at 
the  upper  end  and  as  the  shaking  motion  forces  it  along  the  lightci 


PLATINUM   AND   ALLIED   METALS, 


101 


( (Uistituents  are  crowded  to  the  top  and  forced  over  the  .side,  falling 
into  a  bottom  compartment  whicli  shakes  with  the  table  and  which  can 
lie  used  to  give  a  middling,  or  to  discharge  tailing.  The  concentrate 
travels  the  length  of  the  groove  and  is  tapped  off  throngh  a  spigot  at 
the  end.  Middling  and  tailing  are  tapped  from  the  side  near  the  end. 
Huelsdonk  claims  the  nnit  can  handle  two  cubic  yards  of  gravel  or 
one  ton  of  mill  tailings  an  hour.  Twenty  cubic  yards  of  gravel  give 
two  gallons  of  concentrate.  The  concentration  Avith  mill  tailings  is 
said  to  be  100  to  1.     At  the  La  Grange  dredge  8  tons  of  black  sand 


Photo   No.    10.      Huelsdonk    Submerged   Table    ConcentraEor. 

concentrate  were  reduced  to  about  one-third  of  a  gold  pan  full,  which 
contained  the  year's  output  of  platinum.  Only  ^-horsepower  is  said 
to  be  required  for  the  concentrator.  The  demonstrating  model  has  a 
li-horsepower  engine,  which  is  claimed  to  be  more  than  ample  for 
pumping  water  and  operation.  A  one-iiieli  centrifugal  pump  gives  an 
ample  supply  of  water. 

The  saving  by  this  machine  appears  to  be  very  satisfactory,  and  the 
concentrator  seems  to  liave  a  wide  field  of  application,  but  ought  to 
appeal  especially  to  the  small  miner  or  the  man  who  wants  a  portable 
outfit  which  is  easy  to  operate  and  requires  little  water.  The  installa- 
tion complete,  including  engine  and  pump,  weighs  600  pounds,  and  the 
heaviest  part  is  the  engine.  Two  men  are  required  to  run  the  outfit 
where  hand  shoveling  is  done. 


102  CALIFORNIA    STATE    MINING   BUREAU. 

IDENTIFICATION    AND    METALLURGY    OF    PLATINUM    METALS. 
Detection. 

i\Iauy  of  the  tests  wliich  are  available  for  the  detection  of  platinum 
metals  require  the  metallic  grains  to  be  tested  free  from  other  minerals 
Avhich  are  often  associated  Avith  the  pla.tinnm  and  which  would  give 
interfering  precipitates.  Careful  use  of  the  gold  pan  will  indicate  the 
presence  of  platinum  metals  in  placer  deposits,  even  in  cases  where  these 
metals  are  present  in  very  small  quantity.  They  are  easier  to  save  in 
a  pan  than  gold  and  because  of  higher  specific  gravity  will  lag  somewhat 
behind  it.  ]\Ietals  or  compounds  capable  of  being  confused  with 
platinum  metals  are  rare.  In  a  very  few  northern  streams,  tlie  chief 
one  of  which  is  Smith  River  in  Del  Norte  County,  fine  grains  of  silver 
gray  metal,  highly  nmgnetic  and  noticeably  lower  in  specific  gravity 
than  ordinary  placer  platinum,  have  been  confused  with  platinum. 
These  grains  are  mostly  iron,  although  awaruite/  Ni.^Fe  has  also  been 
identified  in  the  sands  of  this  river.  Similar  grains  from  the  Klamath 
River  gravels  give  no  reaction  for  nickel.  Part  of  the  metal  saved  as 
platinum  at  Klamath  River  properties  is  magnetic ;  other  grains  are  not 
magnetic.  Analyses  of  the  mixed  'crude'  platinum  from  the.se  proper- 
ties show  it  to  be  about  -IS^f  platinum  metals  and  balance  without  value. 
]\Iost  California  crude  platinum  shows  no  magnetic  content  except  the 
accompanying  black  sand. 

Simple  tests  for  the  identification  of  platinum  metals  by  chemical 
means  are  summarized  below : 

The   Glow    Reaction.- 

The  substance  to  be  tested  is  brought  into  solution  by  any  of  the 
common  methods  (in  hot  aqua  regia,  for  example)  and  about  0.2  c.c. 
of  this  solution  is  absorbed  in  a  piece  of  thin  asbestos  paper  by  alter- 
nately dipping  the  paper  into  the  solution  and  heating  until  the 
required  volume  has  been  absorbed.  The  moist  paper,  held  by  one  end 
in  a  pair  of  tongs,  is  heated  to  redness  in  a  Bunsen  flame,  then  removed; 
after  redness  has  ceased,  but  while  the  paper  is  still  hot,  it  is  brought 
into  a  stream  of  mixed  illuminating  gas  and  air  from  a  Bunsen 
burner.  If  platinum  is  present  the  asbestos  paper  will  begin  to  glow. 
The  glow  must  last  for  some  time  and  can  be  brought  back  after  it  has 
once  died  out  by  again  beating  the  paper  and  holding  it  in  the  stream 
of  gas.  The  burner  must  be  arranged  to  supply  a  fairly  good  mixture 
of  gas  and  air,  and  the  pressure  must  not  be  too  great.  For  the  greatest 
sensitiveness  of  the  test  the  solution  should  not  be  too  acid,  the  asbestos 
paper  must  be  very  thin,  and  the  glow  is  intensified  by  having  the 
gas  warm. 


>Cal.  State  Min.  Bur.,  Minerals  of  California,  Bulletin  67,  p.  2  3. 

=Curtman,    L.    J.,    and    Rothberg,    P.  :    Reprint    in    Trans.    American    Metallurgical 
Society  from  Journal  Am.  Cliem.  Society. 


i 


PLATINUM   AND   ALLIED    METALS.  103 

This  test  shows  the  presence  of  as  little  as  0.002  inj;.  of  platiniun, 
005  mg.  iridinni,  .0005  mg.  palladium  or  .0009  mg.  rhodium;  but  does 
not  reveal  osmium  or  ruthenium.     The  test  may  be  applied  successfully 
to  black  sand  concentrates  or  to  solutions  without  preliminarj^  separa- 
tion of  other  substances. 

The  glow  reaction  depends  on  the  catalyzing-  action  of  the  finely 
divided  platinum  compound,  which  hastens  and  intensifies  the  oxidation 
of  the  hydrogen  particularly,  in  the  illuminating  gas. 

Another  simple  method/  which  can  be  followed  in  the  field,  calls  for 
three  chemicals,  nitric  and  hydrochloric  acids  to  form  aqua  regia  and 
potassium  iodide.  A  few  grams  of  the  material  to  be  tested  is  dissolved 
in  a  casserole  by  means  of  acpia  regia,  then  evaporated  to  dryness  on  the 
water  bath  (or  by  gentle  and  uniform  heat).  The  residue  is  heated 
gently  till  every  trace  of  nitric  acid  is  expelled,  as  indicated  by  dis- 
appearance of  the  choking,  acrid  fumes.  The  residue,  containing 
platinic  chloride,  is  dissolved  in  water  and  filtered.  A  few  drops  of 
potassium  iodide  solution  added  to  the  clear  liquid  gives  platinum 
iodide,  which  dissolves,  producing  a  deep  rose-colored  liquid  resembling 
cobalt  nitrate. 

Another  method  provides  for  dissolving  the  residue  from  the  aqua 
regia  solution  in  hydrochloric  acid  and  evaporating  l)y  boiling  till  thick, 
but  not  dry.  This  thick  mass  is  diluted  with  distilled  water  and  a  few 
drops  of  sulphuric  acid  and  a  little  potassium  iodide  are  added.  The 
resulting  solution  is  wine  red  if  considerable  platinum  is  present,  or 
red-pink  Avith  less  platinum. 

Again,  a  solution  of  ammonium  chloride  added  to  the  aqua  regia 
solution  gives  yellow  crystals  of  ammonium-platinic  chloride  if  plati- 
num is  present. 

It  must  be  borne  in  mind  that  these  last  two  tests  are  apt  to  be 
obscured  by  other  elements,  so  the  tests  are  best  made  on  metallic  grains. 

Osmiridium,  in  which  form  California  osmium  occurs,  is  practically 
insoluble  in  a  single  acid  or  in  aqua  regia  so  is  not  susceptible  to  the 
tests  used  to  detect  the  soluble  members  of  the  group.  Osmiridium 
occurs  in  crystalline  pieces  with  hardness  of  6  to  7  and  with  sharp  or 
ragged  edges,  brilliant  tin-like  luster  and  perfect  basal  cleavage  faces; 
being  thus  easily  distinguished  from  the  soft,  thinner,  well-woi-n  and 
duller  colored  platinum  flakes.  The  nuggets  of  platinum  metals  found 
in  California  are  composed  principally  of  osmiridium.  These  are  dis- 
tinguished from  platinum  first  by  their  extreme  hardness,  as  they  can 
not  be  scratched  by  a  knife  or  an  ordinary  file.  Osmium  compounds 
when  heated  at  high  temperature  form  poisonous  oxides  with  pungent 
odor  like  chlorine  gas.  Such  compounds  boiled  in  excess  of  nitric  acid 
give  off  the  tetroxide,  Os0.i. 


'Ohly,  J.  :   Analysis,  Detection  and  Commercial  Value  of  the  Rare  Metals,  p.   61. 


104  CALIFORNIA   STATE    MINING   BUREAU. 

Iridium  occurs  in  soluble  form  alloyed  with  platinum  and  as  an 
insoluble  constituent  of  osmiridium.  Soluble  iridium  separates  as  a 
fine  black  powder  when  the  iridium  sulphate  solution  containing  alcohol 
is  exposed  to  sunlight.  This  powder  is  distinguished  from  platinum 
black  because  it  ha,s  a  much  more  energetic  action  in  oxidizing  gases. 
Iridium  black,  placed  on  a  paper  saturated  witli  alcohol,  causes  the 
paper  to  ignite.^ 

The  identification  of  iridium  in  osmiridium  by  chemical  means  is  too 
involved  for  the  ordinary  prospector  or  experimenter.  The  test  consists 
essentially  of  putting  the  alloy  in  the  form  of  soluble  chlorides  by 
fusing  with  zinc  and  ammonium  chloride.  The  zinc  is  removed  with 
sulphuric  acid,  leaving  mixed  double  chlorides  of  osmium  and  iridium 
as  a  powder.  This  powder  is  dissolved  in  water,  concentrated  by 
evaporation,  acidulated  with  nitric  acid  and  distilled.  The  osmium 
passes  over  and  the  iridium  salt  remains  in  the  residue.  This  salt  can 
be  concentrated  and  the  iridium  precipitated  as  double  chloride  by 
adding  ammonium  chloride  solution.  Spongj'  or  powdery  iridium  is 
obtained  bj'  igniting  the  double  chloride. 

Metallurgy   of   Platinum. 

Most  of  the  Russian  platinum  has  been  marketed  in  years  past  as  a 
rich  concentrate.  IMining  has  been  carried  on  by  a  multitude  of  placer 
miners  working  alone  or  in  small  groups,  using  crude  hand  methods 
and  operating  on  a  very  small  scale.  The  platinum  concentrate  thus 
obtained  is  quite  similar  to  our  California  'black  sand,'  carrying  many 
of  the  same  heavy  minerals  such  as  zirconium,  cliromite  and  magnetic 
iron  oxides.  The  Russian  'crude  platinum'  carries  a  higher  percentage 
of  platinum  and  correspondingly  less  osmiridium  than  the  California 
product.  It  is  also  said  to  usually  carry  enough  alloyed  iron  to  be 
magnetic,  which  is  the  exception  with  the  domestic  material. 

Only  a  small  part  of  the  Russian  product  was  refined  at  home ;  twc 
plants  in  St.  Petersburg  before  the  war  handled  a  few  liundred  pounds^ 
of  concentrate,  and  the  balance  was  exported  to  England,  France  am 
Germany.  The  war  led  first  to  a  curtailment  of  exports,  and  finallj 
chaotic  conditions  in  the  interior  did  a  great  deal  toward  stopping  pro-j 
duction,  and  marketing  through  the  normal  peace  time  channels,  whicl 
had  centered  in  the  capital  city.  Methods  of  refining  have  been  kep^ 
secret  by  the  refiners,  but  the  principles  of  both  the  wet  and  dr 
methods  used  commercially  are  based  on  the  well  known  chemical 
properties  of  different  metals  of  the  group. 

The  wet  method  is  in  commonest  use,  and  its  application  depends  onl 
the  different  degrees  of  solubility  of  the  metals.  Gold  is  first  dissolved! 
out  by  aqua  regia.     Platinum  and  the  small  percentage   of  soluble 


'Ohly,  J.  :  Analysis,  Detection,  etc.,  of  the  Rare  Metals,  p.   79. 


PLATINUM   AND   ALLIED   METALS.  105 

iridium  alloyed  with  it  can  next  be  removed  by  solution  in  stronger 
aqua  regia,  sometimes  used  under  pressure.  Osmium  and  iridium,  as 
the  alloy  osmiridium  (sometimes  called  iridosmine)  remain  in  the 
insoluble  residue.  The  rarer  metals  of  the  group  will  at  this  stage  be 
present  in  very  small  quantity,  possibly  only  as  traces,  in  both  the 
platinum  solution  and  the  osmiridium  residue.  It  is  probable  that  the 
amount  of  them  in  most  California  crude  platinum  is  not  enough  to 
have  a  noticeable  effect  on  the  platinum  itself.  Iridium  alloyed  with 
the  platinum  makes  it  harder,  but  the  alloy  is  suitable  for  many  uses, 
and  hard  platinum  has  been  quoted  lately  several  dollars  higher  j)er 
ounce  than  soft  metal. 

The  separation  of  osmium  and  iridium  is  made  by  volatilizing  the 
osmium  as  previously  outlined.  The  entire  process  of  separating 
platinum,  osmium  and  iridium  requires  two  to  three  weeks.  When 
buyers  offer  paj^ment  in  full  for  all  values  in  'crude  platinum'  on 
delivery,  it  may  be  safely  inferred  that  they  are  simply  estimating  the 
percentages  of  the  various  precious  metals,  and  are  no  doubt  careful  to 
avoid  any  overpajanents.  Another  rather  unsatisfactory  practice  of 
buyers  is  their  tendency  to  pay  for  osmium  and  iridium  as  osmiridium, 
arbitrarily  estimating  the  percentages  of  osmium  and  iridium  without 
separating  them.  On  account  of  the  high  price  established  by  the 
government  for  iridium,  $175  an  ounce,  it  behooves  sellers  to  see  that 
the  separation  is  made,  except  in  cases  where  the  amount  of  'crude 
platinum'  involved  in  too  small  to  warrant  payment  of  the  charge  for 
treatment. 

The  dr}^  method  does  not  give  as  clean  a  separation  as  does  the  wet, 
and  is  not  used  much.  For  dry  treatment  the  ore  is  smelted  in  a 
reverberatory  furnace  with  an  equal  weight  of  galena.  Borax  and 
silica  are  used  as  fluxes.  The  platinum  forms  an  alloy  with  the  lead 
from  the  galena ;  litharge  is  used  to  oxidize  the  sulphur,  and  osmiridium, 
which  does  not  alloy  with  the  lead,  settles  to  the  bottom  of  the  charge. 
This  process  is  much  faster  and  cheaper  than  the  wet  method.  It  can 
be  applied  on  a  small  scale  by  any  competent  assayer  equipped  with  a 
good  furnace,  as  the  lead-platinum  alloy  forms  at  a  temperature  much 
below  the  melting  point  of  platinum. 

For  those  desiring  to  learn  more  of  the  working  details  of  assays  of 
platinum  group  metals,  the  following  references  are  given : 

Mining  and  Scientific  Press.  May  16,  1914,  and  June  20,  1914. 
Mining  and  Engineering  World,  July  13,  1912. 
Ohly,  J. :  Analysis,  Detection,  etc.,  of  the  Rare  jMetals. 

Possibilities  of  Increasing  Platinum  Production. 
A  review  of  conditions  with  which  placer  miners  in  California  now 
have  to  contend  shows  that  we  are  not  justified  in  expecting  any  notable 


k 


106  CALIFORNIA   STATE    MINING   BUREAU. 

increase  in  platinum  production  from  hydraulic  mines.  The  efficiency 
of  recovery  methods  and  the  scale  of  operations  in  our  active  hydraulic 
mining  districts,  are  limited  by  lack  of  water  and  size  of  deposits. 
Many  of  the  bench  gravel  l)odies  of  the  northwest  which  carry  platinum 
are  too  .small  in  area  to  justify  any  large  outlay  for  adequate,  perpetual 
water  supply  or  installation  of  eciuipment  to  give  maximum  recovery. 
Working  as  they  do.  with  such  water  as  is  obtainable  nearby,  their 
operating  season  is  limited  to  five  or  six  months  at  best.  Saving  devices 
such  as  blocks  and  pole  riffles,  with  quicksilver  sprinkled  between,  help 
to  detain  the  coanser  gold.  Platinum  metals  are  uniformly  smaller  in 
grain  size  than  gold  and  there  is  no  doul)t  that  the  amount  of  these 
metals  saved  in  hydraulic  mining  is  only  a  small  fraction  of  that 
entering  the  sluices.  While  in  the  case  of  small  properties  more  care 
in  saving  may  not  be  practicable,  there  are  some  large  and  promising 
gravel  depo.sits  on  Trinity  River,  notably  near  the  mouth  of  its  South 
Fork,  where  there  appears  to  be  ample  acreage  to  justify  an  installation 
(omparal)le  to  that  of  the  La  Grange  mine. 

Resumption  of  hydraulic  mining  to  any  general  extent  in  the  Sierra 
Nevada  would  call  for  a  much  greater  outlay  of  capital  than  is  apt  to  be 
available  for  some  time.  In  addition  to  the  outlay  necessary  to  restrain 
tailing  from  entering  the  rivers,  difficulties  regarding  water  supply 
would  arise.  Many  long  and  expensive  ditches  which  were  built  to 
convey  water  to  hydraulic  mines  have  either  fallen  to  decay  or  have 
been  ac(|uired  by  hydro-electric  companies.  Water  entering  such 
streams  as  the  Feather.  Bear  and  American  rivers  is  being  appropriated 
at  such  a  rate  for  irrigation  and  electric  power  generation  that  the  time 
is  nearby  when  there  will  be  no  unappropriated  water  in  any  of  these 
streams  in  summer. 

Consideration  of  these  points  directs  our  attention  to  the  possibility 
of  increasing  production  from  the  main  source  of  domestic  platinum, 
the    California   dredgers.     Dredging   has   often   been    described   as   a 
branch  of  mechanical  engineering  rather  than  of  mining,  because  soi 
many  of  the  difficulties  have  bieen  problems  of  mechanical  design  and 
construction.     Gold-saving    equipment    has    been    standardized;    steelj 
covered  wooden  riffles  are  largely  used  and  are  set  commonly  at  a 
grade  of  1|"  to  the  foot.     A  good  head  of  water  is  required  to  keep  the 
riffles  from  packing  with  sand ;  and  to  get  the  full  advantage  of  the 
eddying  action  induced  by  the  overhanging  edge  of  the  steel.     Under 
these  conditions  dredger  men  are  prone  to  claim  recovery  of  90%  ori 
better  and  in  general  are  satisfied  to  keep  digging  without  bothering  to 
experiment  with  improved  methods  of  recovery. 

AVith  ample  gold-saving  table  space,  it  is  likely  that  a  satisfactory' 
recovery  is  made  of  gold  which  will  amalgamate.     The  same  can  noti 


PLATINUM   AND   ALLIED    METALS.  107 

be  said  of  'rusty'  gold  or  of  platinum  metals,  on  which  plain  quiek- 
silver  has  no  effect.  The  installation  of  Neill  jigs  in  tlie  Xatonia 
district,  where  'rusty'  gold  is  plentiful,  has  been  the  re.sult  of  failure 
C'f  standard  gold  tables  to  save  such  gold  from  a  gravel  whicli  costs 
more  than  usual  to  dig,  and  where  the  margin  of  profit  had  to  be 
increased.  If  the  more  fortunate  operators  of  the  Yuba  and  Feather 
River  districts  had  been  confronted  with  similar  difficulty,  our  exact 
knowledge  of  precious  metals  lost  Avould  be  sufficient  to  base  a  definite 
f  opinion  on.  To  date,  however,  profits  have  been  so  satisfactory  that 
improvements  have  not  been  required.  As  regards  platinum  especially, 
tlie  total  amount  present  in  the  gravels  has  been  considered  too  trifling 
to  merit  serious  attention.  Tests  were  made  by  variou.s  companies  in 
ibe  Oroville  district  to  determine  the  platinum  content  of  the  ground 
and  the  loss  of  platinum  in  dredging  operations.^  The  loss  of  platinum', 
while  admitted  to  be  appreciable,  was  held  to  be  insufficient  to  warrant 
the  installation  of  concentrating  machinery  to  recover  it.  Such  tests 
were  made  at  a  time  when  platinum  was  worth  only  one-fifth  or  one- 
sixth  its  present  value.  All  the  platinum  of  the  central  dredging 
fields  in  California  is  fine  in  size  and  most  of  it  is  in  such  thin  flakes  as 
to  be  easily  floated  on  water.  It  is  only  reasonable  to  assume  that  more 
platinum  goes  back  into  the  pond  than  remains  on  the  tables. 

The  only  recently  reported  investigation  of  such  losses  was  made  by 
James  Neill  on  the  Yosemite  dredge,  near  Snelling.  This  dredger  is  a 
small  one,  containing  machinery  from  the  old  Indiana  No.  1,  which 
was  wrecked  in  March,  1907,  after  six  years  service  in  the  Feather 
River  district.-  Neill  states  that  in  22i  months,''  platinum  to  the  value 
of  $3138  was  recovered  on  that  dredger,  indicating  a  monthly  average 
of  $150.  Samples  taken  by  Neill  from  the  tailing  after  passing  the 
Neill  jig,  represented  an  entire  cut  across  the  pond.  lie  found  the 
tailing  carried  35,037  lb.  dry  weight  of  sand  in  a  22-hour  day.  A  test 
of  the  tailing  by  the  General  Engineering  Company  of  Salt  Lake  City 
on  a  Wilfley  table,  gave  1.81%  concentrate  and  7.25%  middling.  The 
concentrate  was  refined  by  Shreve  &  Company  of  San  Francisco,  who 
reported  half  an  ounce  of  platinum  metals  a  ton.  An  analysis  of  a 
recent  shipment  of  the  platinum  metaLs  from  this  ground  sliowed 
97.7%  platinum  and  2.3%  osmiridium,  a  remarkable  degree  of  purity 
for  placer  platinum,  and  the  highest  grade  ever  reported  from  a 
California  producer. 

Basing  his  calculations  on  these  tests,  Neill  went  further,  and  figured 
that  during  an  average  month  the  dredge  was  losing  9.5  tons  of  concen- 
trate carrying  4.75  ounces  of  platinum  metals,  or  about  three-fourths  of 


I 


'Cal.   State  Mln.  Bur.,  Bulletin   '>7 .  p.   81. 

=Cal.   State  Min.  Bur.,  Bulletin  57,  p.   117.  tj„„„„    r.^^    «    1017 

^Recovery  of  platinum  in  gold  dredging.     Mining  and  Scientific  Press.  Dec.  8,  1917. 


108  CALIFORNIA   STATE    MINING   BUREAU. 

all  the  platinum  in  the  gravel  handled.  In  spite  of  the  predictions  of 
experts  who  forecasted  failure,  he  installed  a  one-half  size  Wilfley  table 
on  the  upper  deck  of  the  dredge.  The  tailing  from  the  jigs  is  elevated 
\>\  a  Krogh  sand  pump  to  a  tank  on  fhe  upper  deck,  going  thence  to  the 
Wilfley  table.  The  table  is  said  to  work  well  under  normal  digging 
conditions. 

The  application  of  such  tests  to  the  tailing  from  dredgers  in  the  three 
larger  districts  on  the  Feather,  Yuba  and  American  rivers  Avould  be 
timely  now,  and  there  appears  to  be  no  logical  objection  to  the  tests 
from  the  standpoint  of  cost.  If  the  same  encouraging  results  were 
obtained,  the  added  saving  of  platinum  would  be  no  small  item  to  the 
producers  and  to  the  country  at  large.  While  of  course  unsafe  to 
generalize  too  freely,  it  may  be  said  that  tlie  rate  of  yield  of  platinum 
from  our  various  dredging  fields  in  central  California  does  not  vary 
widely,  and  percentage  of  recovery  is  probably  also  comparable  where 
saving  equipment  is  ample  and  where  working  conditions  are  alike,  as 
regards  bedrock  and  quality  of  gravel.  Such  considerations  jiLstify  the 
assumption  that  results  of  the  tests  at  the  Yosemite  dredger  might  be 
duplicated  elsewhere. 

The  relative  merits  of  the  different  types  of  concentrators  which 
might  be  used  for  this  work  .can  only  be  established  by  working  tests. 
The  capacity  of  a  large  modern  dredge  is  such  that  it  would  require  an 
immense  amount  of  equipment  to  take  care  of  the  tailings  with  tables 
unless  the  volume  could  be  first  cut  down  by  a  rough  preliminary 
concentration. 


PLATINUM   AND   ALLIED   METALS. 


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INDEX. 


Page 

Alta  Bert  Dredging  Company 34 

American    Gold    Dredging    Company 22,  37 

American   River  district,   dredging  in 27—30 

ratio   of   platinum    to    gold    in 28,  29 

Analyses  of  platinum  metals  from  California,   table  of 109 

Analysis  of  platinum  from  Micliigan-Salmon  mine 79 

Ten   Eyek  mine 67 

Area  of  dredging  ground  in  Oroville  district 20 

Yuba  River   district 23 

Ashburton    Mining   Company 27 

Assay  of  platinum  from   Mendocino  County 47 

of  sand  residue  from  Rosalina  mine 67 

of  sea  beach  concentrates 42 

Assaying  of  platinum   metals 105 

Awaruite,  mistaken  for  platinum 102 

Assays   of  black   sand   concentrates,    Cosumnes   River 31 

of  platinum   from   P'olsom-Natomas   district 28 

from   La  Grange  Gold   Dredging  Company 33 

of  product   of  Valdor   dredge 85 

Beach   deposits 41-43 

Bear  River,  dredging  in 39 

costs  of  dredging  in ' 39 

Beebee    claims    92-93 

Beegum    Creek,    platinum    in 48-52 

results  of  pannings   on 49 

Bell  Gulch  deposits 94 

Big    Flat    deposit 61 

Big  Lagoon  Mining  Company 42 

Big  Oak  Flat  deposit 88 

Black    Bear   deposit 73,  74 

Bear  lode,  production  of 77 

Black  Sand 41,  42,  46,  47,  65 

tests  on.  at  Valdor  dredge 85 

Sands,   analyses  of  California 43 

recovery  of  platinum  from 91—101 

Blister  copper,   platinum   in 93 

Bloomer   mine    75 

Blue   Nose   mine 68 

Tent    district    26 

Bondo   mine   66 

Borden,   Ivy  L.,   dredge  of 33 

Butte  Dredging  Company 19,  33 

Butte  Creek,  dredging  on 38-39 

cost  of  dredging  on 39 

Calaveras  Dredging  Company 32 

River  dredging  district 32-33 

area    of    32 

costs  of  dredging  in 32 

production  of 33 

tenor  of  ground 32 

California  State  Mining  Bureau,  cited 20.   3S,   3!),   41.   6(1.   61.   74.   89,  95.   102.   107 

Calpella,  platinum   deposit  at 46-47 

Carpenter  property 88-89 

Carrier   Gulch   deposits 92 

Cavanaugh  mine °^ 

Chapman  mine °^ 

Christensen,  Nels,   hydraulic  mine 60 

Chromite  deposits  in  Del  Norte  County 58 

on  Hayfork  of  Trinity  River 91 

occiu-rences  in  American  River  district 28 

Cinnabar    in    gravel ^^ 

Clear  Creek  dredging  district 38 

Desilhorst  operations   in 38 

Gardella    operations    in 38 

Coffee  Creek,  dredging  in ^'* 

8—46903 


114  INDEX. 

Page 

Colorado-Facific  Gold  Dredging  Company 27 

Concentrate,   recovery   of  platinum  from 96-101 

Cook,   Geo.,   mining  operations  by ^ 59 

Copper  depo.sit.s  in  Del  Norte  County 62 

Corona   de   Oro   mine 89-90 

tenor  of  gravel   at 90 

Cost  data,   dredging  costs  on  Bear  River 39 

Butte  Creek 39 

Clear   Creek   38 

Merced  River 34 

Mokelumne   River 31 

of  El  Oro  Dredging  Company 32 

Yosemite  Gold  Dredging  and  Mining  Company 34 

drilling  prospect  holes  in  dredging  ground 19 

installing  Hardinge  Mill   on  dredge 11) 

Neill    jigs    on    dredge 19 

Cosumnes  River  dredging  district 30-31 

area    of    30 

production    from    31 

Cottonwood  Creek,  dredging  district 38 

Craigs  Crook,  mining  on 62-63 

Curtman,  L.   J.,  and  Rothberg,   P.,   cited 102 

C.vanide  treatment  of  black  sand  concentrate 99 

Darnell,  J.  M.,  operations  of - 62 

Day,  David  T 10 

Del  Norte  County 

chromito   deposits    in 58,  62 

copper  deposits  in 62 

distribution   of  platinum   in 58-63 

di-ainago  and  water  resources  of 56-57 

gcologj-    of    57—58 

li>'draulic  mining  in 55-64 

(H-igin  of  platininn  in 63-64 

platinum  in  place  in , 94 

sea  beach  operations  in 41 

topography  and  relief 55—56 

Detection  of  platinum  metals 102-104 

Deville  and  Debray,  cited 11 

Diller,    J.    S 15 

cited 40,  56 

Doul)le-stacker  dredge 18 

Drainage  of  Del  Norte  County 56-57 

Salmon   River   district 68-72 

Dredges,    equipment    of 18-19 

Dredging    18-40 

American   River  district 27-30 

Bear  River 39 

Butte  Creek 38-39 

Calaveras   River   32-33 

Clear   Creek   38 

Cosumnes    River   3  0-31 

Cottonwood  Creek 38 

Feather  River  di.strict 2  0-23 

Folsom-Natoma  district 27-29 

Introduction    18-19 

Klamath    River   36-37 

Merced  River 33-34 

Mokelumne   River 31—32 

Newer  fields,   summary  of 34—40 

other   streams   39-40 

prospecting  ground   for 19—20 

Sacramento  River 37 

Scott  River 37 

Trinity    River    34-36 

Tuolumne    River    33 

Upper  American  River 29-30 

Yuba  River   district 23-27 

Dredging  Land,  prices  paid  for 20 

in  Hoopa  Valley  Indian  Reservation 35 


INDEX.  115 

Dredging  recovery  methods  Page 

recovery    of    platinum 97—101 

platinum    losses    in _107— lOS 

Drift  mining  on  Klamath  River 67    gg 

Drilling,  to  prospect  dredging;  ground 19—20 

cost     of     J9 

Duncan  Springs,  platininn  occurrence  at 4.I 

geology  of  deposit  at 44-48 

Eilers,    A.,    cited 93 

El  Dorado  and  Placer  Counties  Gold  Mining  and  Power  Company 29 

Eldredge,   Irving 69,   75,    81 

Elevator,   use   of 54 

Elkliorn    mine    5!) 

El   Oro   Dredging  Company 32,  39 

Equipment  of  dredges 18-19 

for  recovery  of  platinum  from  concentrate 97-101- 

Estabrook  Gold  Dredging  Company 34 

Evans,   R.   D 23 

Feather   River   district,    dredging   in 20-23 

method  of  recoving  platinum  from  concentrate  in 97-98 

production   of  platinum,    1917 22 

Ferguson,  Henry  G 11,   89,   94 

Field  method  for  testing  platinum 103 

Florence   mine    65 

Folsom-Natoma   district,    dredging   in 27-29 

French     Hill     deposits 62 

Gaylord,    Edward    29 

Gardella,  Lawrence,  dredging  operations 22,  38,  39 

Gem   placer   mine 89 

Geography  of  areas  covered 14-15 

Geology  of  Del  Norte  County , 57-58 

Duncan    Springs  deposit 4  4-48 

Junction    City   district 82-83 

Salmon   River   district 72-78 

George  Washington   placer  claims 59 

Gilta   mine    , 73,  77 

Glow  reaction  for  detecting  platinum 102-103 

Gold   Hill    district,    dredge   operations   in 39 

placers,   association  of  platinum   in 18,  34 

Grade  of  Salmon  River 71 

Greenhorn  Creek,   dredging  on . 36 

Hammer  property 86—88 

ratio  of  platinum  to  gold  on 87 

Hammon,   W.    P 23 

Hanks.   A.  A.,   cited 47 

Hardinge  mill,   installation  cost  on  dredges 19 

Harrison  Gulch  deposits 93 

Hawkins  Bar  property 89 

Hayfork  Creek.      (See  Hayfork  of  Trinity  River) 

Hayfork  of  Trinity  River,  early  days  production 93 

hydraulic   mining   on 90-93 

Hellman,   C.   F.,  washer  used  by 19 

cited 32 

Henderson   mine   , 89 

Hershey.  O.  H.,  cited 58.  68,  76,   78,   86 

Hertevant  mine.      (See  Valdor  dredge) 

Highland    mine    77 

Homestake  mine  __ 77 

Honcut   Creek  district 20 

Hopland  deposit.      (See  Duncan  Springs) 

Hoopa  Valley  Indian  Reservation,  dredging  ground  within 35 

Howell    Placer    mine 44-4  8 

Huelsdonk  Submerged  Table  Concentrator,  description  and  use  of 100-101 

Humboldt    County,    seabeach   opei-ations   in 41-42 

Hurdy    Gurdy   Creek,    mining   on 61 


116  INDEX. 

PAGE 

Hydraulif   Mining 52-93 

Del    Norte    County 55-64 

Hayfork   of   Trinity   River 90-93 

Introduction    52-55 

Junction    City   district 82-85 

Klamath    River    64-68 

Lower  Soutli  Fork  and  Main  Trinity  River 85-90 

Salmon    River   district 68-82 

Hydraulic  mining  recovery  methods 96-97 

Identification    of   platinum    metals 102-104 

field    method   for 103 

Indiana   Gold   Dredging   Company 30 

Introduction    9—17 

geography   of  area   covered . 14-15 

properties,   uses  and  world  supply  of  platinum  metals 11-14 

purpose  and   scope  of  the   Report 9-11 

topography  and  relief  of  area  covered 15—17 

Iridium 12,   25,   28,   29,   38,   47 

tests   for    104 

Iron  Mountain  mine,  platinum  in  blister  copper  from 93 

Jones  Creek,   mining  on 61 

Junction    City   district 82-85 

introduction    82 

geology  of 82-83 

production   of  platinum   in , 84-85 

Kaus  mining   operations 63 

Kellogg  black-sjind  macliine,   description  and  use  of 98 

Kingsbury    Gulch    deposits 92 

King    Salmon    mine 77 

Klamatli   mine 73 

Klamath    River,   dredging   field 36-37 

drift  mining  on 67,  68 

liydraulic    mining    on 64-68 

River  mine 64-65 

ratio  of  platinum  to  gold  in 65 

Knight,  Geo.  H..  ranch  deposits 91 

Koon   Ranch   property 88 

Kunz,   G.    F.,   cited 12 

La  Grange  Dredge,  method  of  recovering  platinum 100-101 

La  Grange  Gold  Dredging  Company 33 

assay    of    product    of 33 

method  of  recovery  used  by 33 

La    Grange    mine 52 

Land,    Gordon,    operations    of 62 

Land   under   tide  water,   laws   affecting 42-43 

Lanky    Bob  mine 77 

La   Plata   claim 96 

Laws   affecting   land    under   tidewater 42-43 

Lawson,   A.   C,   cited 73 

Letter    of    Transmittal . 7 

Lindgren,  W.   10 

Lindley,    Curtis   H.,    cited 42 

Little  Creek  deposits 92 

Long  torn,   description  and   use  of 97 

Los  Angeles   County,   operations   in 40 

Lower  South  Fork  and  Main  Trinity  River 

hydraulic    mining   on 85—90 

terrace    deposits    of 86-87 

MacBoyle,    E.,    cited 40 

MacDonald,    D.    R.,    cited 52 

Manganese,   in   Salmon  River  district 73 

Mann  and  Ross  drift  mine 68 

ratio  of  platinum  to  gold  in 68 

Maple    Creek    deposits 94,  95 

Marysville  Dredging  Company 23,   24,  25 

method  of  recovering  platinum 99 


INDEX.  117 

PAGE 

McAdams    Creek,    dredging   on 37 

Mendocino   Countj-,    platinum   occurrences   in 44—18 

geology   of   deposits    in 44-48 

Merced   River   district,   dredging   in 33-34 

Metallurgj'   of    platinum    metals . 104-105 

wet   methods    104-105 

dry    methods 105 

Method  of  recovering  platinum,  from  concentrate 96-101 

on    Valdor    Dredge 85 

Michigan-Salmon    Mining    Company 54 

iRuble    elevator    used    at 54 

-Salmon    mine    77,    78,    79 

analysis  of  platinum  from 79 

^Mining  and   Engineering  World,   cited 105 

Mining  and   Scientific  Press,   cited 94,    105,    107,    109 

Jlokelumne  River  district,  dredging  in 31-32 

n         area    of    dredging    ground 31 

'■  platinum    production    of 32 

INIonkey    Creek    mine 59 

Mountain  Meadow   district,  proposed  dredging  operations   in 40 

Myrtle   Creek   Placer   Mining   Company 59 

Xatoma   district,  method  of  recovering  platinum   in 100 

(See,   also.   Folsom-Natoma   district) 

Xatomas   Consolidated   of   California 20,    21,    27,    29 

I         metliod   of   recovering  platinum 97-98 

'  production   for   1917 27 

Neill,   James,   investigation  of  platinum   losses  in   dredging 107-108 

Neill  jigs,  on  dredges 19,   27,   107 

installation    costs    19 

Nevada  County,   platinum   in   place   in 96 

Newer    dredging    fields 34—40 

Bear    River    39 

Butte  Creek 38-39 

Clear    Creek     38 

Cottonwood    Creek    38 

Introductory    34 

Klamath    River    36-37 

other    streams    39-40 

Sacramento    River 37 

Scott    River    37 

Trinity    River    34-36 

Xiger  Hill  hydraulic  mine 79 

North  Fork  placer  mines,  production   of , 77 

Nuggets  of  platinum  metals 14,   79,  80,   82,  94 

Ohly,   J.,   cited 103,    104,    105 

Orcutt    hydraulic    mine 80 

Origin  of  platinum  in  Del  Norte  County t^~ti 

of  placer  gold   in   Salmon   River   district 76-77 

Orleans    Basin,    deposits    in 66 

Oro    del    Norte    Company ■*! 

Oroville   district,   area   of   dredging   ground   in 20 

( See,  also,   Featlier   River  district ) 
Oroville    Dredge,    Limited -1-  35 

Dredging  Company 39 

Oro  Water,  Light  and  Power  Company 31,   36 

Osmiridium 12,  13,   14,  25,  38.  47,  65,  67,  79,  SO.  82,  107 

tests   for    ^2? 

Osmium 12.  U.  25,  28.  47.  103,   105 

separation    of.    from    iridium 1"^ 

Palladium   Z"'^v}^'  II 

Pacific  Gold  Dredging  Company 21,  23.  24.  29.  34.  38 


Peterson,     Roy,     claim 
Peterson  mine 
Placer  gold  in 


80 


Salmon  River  district,   origin   of ^^"al 

Placerville    Republican,    cited 


118  INDEX. 

PAGE 

Platinum,    dredging   operations 18-40 

liydraulic   mining  operations 52—93 

in  blister  copper 93 

in    place    93-96 

losses     in    dredging 107-108 

minor    occurrences    44—51 

natural   alloys    of 11,  12 

recovery   from   concentrates 96-101 

sea  beach  deposits   of 41-43 

Platinum   metals,   association   of,   in  gold  placers 18 

geography   of   deposits   of 14—17 

identitication    of    102-104 

metallurgy    of    104-105 

production  of,   in  California,   1887-1918 17 

production,    possibilities   of    increasing 105-108 

(See,   also,   Production  of  Platinum) 

properties  and   uses  of 11-14 

table  of  analyses  of 109 

producers  In   California,    1917 110-111 

world    supply    of ' 11-14 

Possibilities   of    increasing   platinum    production 105-108 

Prindle,    L.    M 11,  94 

Producers  of  platinum  metals   in  California,    1917,   table  of 110-111 

Production    of   platinum 

Black   Bear  lode 77 

Calaveras    River    district 33 

Cosumnes  River  district 31 

Folsom-Natomas    district    28-29 

in    California,    1887-1918 17 

Junction    City    district , S4— 85 

Mokelumne    River    district 32 

Natomas   Consolidated,    1917 27 

North  Fork  placer  mines 77 

possibility    of    increasing 105-108 

upper    Yuba   River 26 

Yuba    River    dredges 24 

Properties  of  platinum   metals 11—14 

Prospect   Creek   deposits 92 

Prospecting    dredging    ground , 19-20 

Putali   Creek,   platinum   in 50-51 

Ratio  of  platinum  to  gold 

American    River    field 28,  29 

Hammer    property    87 

Klamath   River  mine 65 

Mann   and   Ross   drift   mine 68 

Yuba    River    field 25 

Valdor  Dredge   property 85 

•Recovery  of   platinum   from   concentrate 96-101 

dredging  practice    97-101 

Feather    River    method 97-98 

hydraulic   mining   practice 96—97 

La    Grange    method 100-101 

Natoma    district    method 100 

Yuba    River    method 99 

Red  Hill  mine.      (See  Michigan-Salmon  mine) 
Relief.      (See  Topography) 

Rhodium    14,  29 

Rocks  of  Salmon  River  district 73-76 

Rosalina  mine 67 

assay  of  sand  residue  from 67 

Rothberg,   P.,  and  Curtman,   L.  J.,   cited 102 

Ruble   elevator,    description   and  use 54 

Ruddock,   George  T.,   cited 50 

Sacramento  River  field 37 

area   of  dredging  ground 37 

Salmon   River,   grade   of 71 


INDEX.  ]  1 1) 

PAGE 

Salmon   River   district 68-82 

drainage  and  water  resources  of 68-72 

geology    of    72-78 

manganese  occurrence  in 73 

occurrence  of  platinum  in 77-82 

origin  of  placer  gold  in 76-77 

rooks  of 73-76 

terrace  deposits  in 76 

topography   and  relief  of 68-70 

Salstrom  mine 65-66 

San  Bernardino   County,  platinum  in  place  in 94 

San   Francisco  County,   sea  beach  operations   in 41 

San  Luis  Obispo  County,  platinum  in  place  in 95-96 

San  Mateo  County,  sea  beach  operations  in 41 

Santa  Cruz  County,   sea  beach  operations  in 41 

Scott  River,  dredging  in 37 

Sea-beach    concentrates,    assay   of 42 

Sea    beaches    41-43 

analj-ses  of  black  sands  of 43 

Del  Norte  County  operations 41 

Humboldt    County    operations 41-42 

introductory   41 

laws   affecting   42-43 

Serpentine,    platinum    in 96 

Shasta   County,    platinum   in 48—50 

platinum    in   place   in 93 

Shasta    Dredging    Company 38 

Sherwood,  A.   H.,  method  of  recovering  platinum 98 

Siskiyou   Dredging  Company 37 

Slim    Jim    mine 77 

Smartsville    district,    dredging   operations   near 39-40 

Smith,  J.  F..  cited 73,   74,  82 

Smith  River,  hydraulic  mining  on 58—64 

terrace    deposits    of__ 64 

South  Fork  Gold  and   Platinum  Mining  Company.      (See  Hammer  property) 
Strouse,   E.   E 100 

Table  of  analyses  of  platinum  metals  from  California 109 

producers  of  platinum  metals  in  California,   1917 110-111 

production  in  California,  1SS7-191S 17 

Tehama   County,   platinum    in 48-50 

Ten  Eyck  mine 67-68 

analysis  of  platinum  from 67 

Tenor  of  gravel  at  Corona  de  Oro  mine 90 

Terrace   deposits,   of  Lower  South  Fork  and  Main   Trinity  River 86-87 

Salmon    River  district 76 

Smith    River    64 

Tests,  for  platinum  metals.      (See  Identification  of  platinum  metals) 

on  black   sand  at  Valdor  dredge 85 

Thompson   Peak,   elevation   of 70 

Tibbetts,    S.    A 13 

Top   Notcji  mine 89 

Topography  of  areas  covered 15-17 

of  Del  Norte  County . 55-56 

of  Salmon   River   district 68-70 

Trinity  County-,  platinum  in  place  in 94-95 

Trinity  Gold  Dredging  Company 35 

Trinity  River  Dredging  field 34-36 

Trinity  River,  Hayfork  of,  hydraulic  mining  on 90-93 

Tuolumne   River,   dredging  in 33 

Upper  American  River,   dredging  in 29-30 

Feather  River,   dredging  in 22 

Yuba  River,  production   from 26 

U.   S.  Geological  Survey 43,   67,   91 

cited 28 

Uses  of  platinum   metals 11-14 


120  INDEX. 

Page 

Valdor   dredge 35 

dredge    property    84 

ratio  of  platinum  to  gold  in 85 

metliod    of   retovery    used 85 

tests  on  black  sand  at 85 

assays  of  product  of 85 

Waring,   C.   A.,   cited 40 

Water  resources  of  Del   Norte  County 56-57 

Salmon   River   district 68-72 

Weitchpec  deposits 64 

West  End  mine,   platinum  in  place  in 94 

Wheeler,    A.    A.,    cited 95 

Wike,  Wm. 13 

operations  of — 80-82 

Wilkes-Barre    Dredging    Company 27 

Willow  Creek,   platinum   on : 29 

World  supply  of  platinum  metals 11-14 

Wyman's   Ravine  district 20 

Yolo   County,    platinum   in 50-51 

Yosemite  dredge   19 

Gold  Dredging  and  Mining  Company 33 

dredging  costs   of 34 

Yuba  Consolidated  Goldflelds 23,    24,    26 

method  of  recovering  platinum 99 

Yuba    River    district 23-26 

area   of  ground 23 

method  of  recovering  platinum  used  in 99 

production    of    24 

ratio  of  platinum  to  gold  in 25 


46903     2-20     IM 


j|i 


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THIS    BOOK    IS    DUE    ON    THE    LAST    DATE 
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WILL  BE  ASSESSED  FOR  FAILURE  TO  RETURN  THIS  BOOK 
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SEVENTH  DAY  OVERDUE. 


I  r- '- 


DEC  1  1 


f—    f"^  ,f^'',  ,      "•-   J       ■      1   > 


0 


INTERimRARY  LOAI 
SENT 


DEC  11  1991 


"uc  DAVIS  -  icr 


JAN  15  1992 
RETURNED  ^ 


a 


THYS  SCi  LIB 


Booi  SJip-20m-5 '59(A2537i^)458 


iai52i. 


Calif.  Dept.  of  natural 
resources,  Div.  of  mines 
Bulletin* 


n 


(X 


l\^. 


PHYSICAL 
CIENCES 
LIBRARY 


c« 


Call  Numbeo: 

TN2ii 
C3 
.      A3 
no.  65 

T/v;?4 

C3 
A3 


LIBRA**  ^ 

tmivERsiTY  OF  csurommk 

DAVIS 

181593 


431 


3   1175  00459  4118 


